The Necessity of Following Sunnah in Both Fundamentals and Subsidiary Matters

Author: Sheikh Abdul Mohsin Al-Abbad

According to the teachings of the Book and Sunnah, just as it is obligatory to follow the Sunnah of the Messenger of Allah (صلى الله عليه وسلم) in matters of belief, it is equally necessary to adhere to the Sunnah in subsidiary issues where ijtihad (independent reasoning) is permissible once the evidence has become apparent.

The Prophet (صلى الله عليه وسلم) said:

"For indeed, whoever among you lives long will see great differences; so you must follow my Sunnah and that of the rightly guided caliphs."
[Sunan Abi Dawood: 4607, Musnad Ahmad 4/127, Hadith 17145, Al-Mawsu'ah Al-Hadithiyyah 28/375, Al-Mawaarid 102, Musnad Darimi 1/45, Hadith 96]

The predecessors of this Ummah, including the four Imams – Abu Hanifa, Malik, Shafi'i, and Ahmad – gave similar advice. They emphasized that one should adopt a position based on evidence, and if a sound Hadith from the Messenger of Allah (صلى الله عليه وسلم) contradicts their statements, then their statements should be abandoned.

Imam Malik's famous saying is widely known:

"Everyone's statement can be accepted or rejected, except that of the Messenger of Allah (صلى الله عليه وسلم)."
(Note: This statement is without a connected chain. It has not been found with an unbroken chain of transmission. See also [Muqaddimah Sifat al-Salah al-Nabi (صلى الله عليه وسلم), p. 103])

Imam Shafi'i (رحمه الله) stated:

"There is consensus among the people that whoever the Sunnah of the Messenger of Allah (صلى الله عليه وسلم) is made clear to, it is not permissible for him to leave it for anyone's statement."
[Kitab al-Ruh by Ibn Qayyim, p. 395, 396]

Before quoting this, Ibn Qayyim wrote:

"The one who presents the statements of scholars and compares them with the texts, and rejects what contradicts the texts, is not undermining their statements or being disrespectful towards them. Rather, he is following them, for they all instructed this. Thus, their true follower is the one who acts upon this advice, not the one who contravenes it."

Some scholars who were engaged in the jurisprudence of the four Imams also transmitted that if the statements of the Imams contradicted the authentic evidences, they relied on the evidences. For instance, Asbagh bin al-Faraj said:

"Wiping over the socks during the state of ritual purity is more established for us from the Prophet (صلى الله عليه وسلم) and the leading Companions than the statement of Imam Malik."
[Fath al-Bari: 1/306]

Hafiz (رحمه الله) stated in Fath al-Bari (1/276):

"Maliki jurists do not consider it necessary to clean the vessel with soil if a dog licks it. Al-Qarafi (a Maliki scholar) said: 'Authentic Hadiths have reached the level of authenticity on this matter, so it is surprising that they did not adopt a stance according to these Hadiths.'"

Ibn Arabi Maliki said:

"Maliki jurists say that the funeral prayer in absentia was specific to the Prophet (صلى الله عليه وسلم). We say: 'Whatever action the Prophet (صلى الله عليه وسلم) performed, his Ummah should also perform because the principle is non-specificity.' They say that the earth was folded for the Prophet (صلى الله عليه وسلم) and the body was presented to him. We say: 'Our Lord is capable of this, and it was befitting of our Prophet (صلى الله عليه وسلم), but only say what has reached you through transmission, do not invent from yourself. Only mention established Hadiths and narrations. Leave weak narrations because their result will be irreplaceable harm.'"
[Fath al-Bari: 3/189, Nayl al-Awtar by Shawkaani: 4/54]

While discussing the determination of the middle prayer (Asr), Ibn Kathir (رحمه الله) wrote:

"The Hadith has reached the level of authenticity that it refers to the Asr prayer, so there is no way but to accept it." He then quotes Imam Shafi'i (رحمه الله): "Any of my statements that contradict a sound Hadith from the Prophet (صلى الله عليه وسلم), the Hadith takes precedence, and do not follow my statement." He also said: "When a Hadith reaches the level of authenticity and my view contradicts it, then I retract my view, and my view is what is established from the Hadith of the Prophet (صلى الله عليه وسلم)." After quoting this, Ibn Kathir (رحمه الله) wrote: "This indicates his great trustworthiness. The same was said by all his brothers, the noble Imams. May Allah have mercy and be pleased with them. Ameen. Based on this, Qadi Mawardi wrote explicitly that Imam Shafi'i's position is that the middle prayer is Asr, although he specified in his later opinion that it refers to Fajr. A group of Shafi'i scholars among the hadith narrators also agreed with this position. Alhamdulillah."
[Tafsir Ibn Kathir 1/587, verified by Abdul-Razzaq al-Mahdi]

Hafiz Ibn Hajar stated in Fath al-Bari (2/222):

"Ibn Khuzaymah wrote about raising the hands when getting up from two rak'ahs that it is Sunnah, even though Shafi'i did not mention it. Hence, the chain is authentic, and Shafi'i said to adhere to the Sunnah and leave my statement."

In Fath al-Bari (3/470), Bayhaqi narrated in Ma'rifah (al-Sunan wa al-Athar 3/54, Hadith 1934, with an authentic chain) through Rabi (a special student of Shafi'i) that Imam Shafi'i said:

"A Hadith is narrated regarding women going out to the prayer area on Eid. If it is authentic, then that is my stance." He referred to the Hadith of Umm Atiyyah (رضي الله عنها). Thus, it is obligatory for the Shafi'is to adhere to it.

Imam Nawawi mentioned in Sharh Muslim (4/49) after discussing the scholars' disagreement on breaking wudu by eating camel meat:

"Ahmad bin Hanbal and Ishaq bin Rahwayh said that there are two Hadiths on this matter, one narrated by Jabir (رضي الله عنه) and the other by al-Bara' (رضي الله عنه). This stance is stronger, even though the majority opposes it."

Hafiz Ibn Hajar narrated in the explanation of the Hadith of Abdullah bin Umar (رضي الله عنه) about the command to fight people, mentioning the discussion between Abu Bakr (رضي الله عنه) and Umar (رضي الله عنه) regarding the rejecters of Zakat. He wrote:

"This incident is proof that the Sunnah can be hidden from senior Companions while a common person is aware of it. Thus, one should not look towards opinions when the Sunnah is present, even if those opinions seem good. If they contradict the Sunnah, they should not be considered. And it should not be said that how can this Sunnah be hidden from such a person."
[Fath al-Bari: 1/76]

In Fath al-Bari (3/544), he stated:

"Marking the Hadi (sacrificial animals) is the opinion of the majority among the Salaf and Khalaf. Tahawi narrated in 'Ikhtilaf al-Ulama' from Imam Abu Hanifa that it is disliked, while the other Imams consider it mustahabb (recommended) in following the Sunnah, including his students like Muhammad and Abu Yusuf, who also viewed it favorably."

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All Innovations are Misguidance, There is No Good Innovation​

All innovations are deviations and misguidance, as indicated by the general statements of the Prophet (صلى الله عليه وسلم) narrated by Jabir and Irbad (رضي الله عنهما):

"Every innovation is misguidance."
[Sunan Abi Dawood: 4607]

And the Prophet's (صلى الله عليه وسلم) statement:

"Every innovation is misguidance"
clearly indicates that anyone who claims or believes that there is a good innovation in Islam, their statement and belief are false.

Furthermore, Abdullah bin Umar (رضي الله عنهما) said:

"Every innovation is misguidance, even if people see it as good."
[Al-Sunnah by Al-Marwazi: 82]

Regarding the Prophet's (صلى الله عليه وسلم) statement:

"Whoever introduces a good practice in Islam will have its reward and the reward of those who act upon it after him without diminishing their rewards. And whoever introduces a bad practice in Islam will bear its burden and the burden of those who act upon it after him without diminishing their burdens."
[Muslim: 1017]

It is not permissible to argue that there is a good innovation in Islam based on this statement, because it refers to initiating established righteous actions, as indicated by the cause mentioned in the Hadith before it. The summary of the event is that some people from the tribe of Mudar came to Medina showing signs of poverty. The Prophet (صلى الله عليه وسلم) encouraged charity, and a person from the Ansar brought a bag that was difficult for him to carry (then people began to bring their charities one after another). The Prophet (صلى الله عليه وسلم) said: "Whoever introduces a good practice in Islam..." (reference mentioned). Similarly, reviving a forgotten Sunnah in a place where it was not known is included in its meaning. However, interpreting it to mean introducing new things into the religion is not permissible, because the Prophet (صلى الله عليه وسلم) said:

"Whoever innovates something in our matter (religion) that is not from it, it will be rejected."
[Sahih Bukhari: 2697 and Sahih Muslim: 1718]

The Shariah is complete and does not need innovations and new things. Introducing innovations is, in fact, an accusation of incompleteness and deficiency in the Shariah, as mentioned in the statement of Imam Malik (رحمه الله). Also, the statement of Abdullah bin Umar (رضي الله عنهما):

"Every innovation is misguidance, even if people see it as good."
[Al-Sunnah by Al-Marwazi: 82]

Imam Malik (رحمه الله) also said:

"Whoever introduces an innovation in Islam and considers it good has claimed that Muhammad (صلى الله عليه وسلم) has betrayed the message because Allah says: 'This day I have perfected for you your religion.' So whatever was not part of the religion on that day cannot be part of the religion today."
[See Al-Hadith: 15 p. 33]

As for Umar (رضي الله عنه) gathering people to pray Taraweeh behind one Imam, this is an example of manifesting and reviving a Sunnah because the Prophet (صلى الله عليه وسلم) led people in the prayer of Qiyam al-Ramadan on some nights of Ramadan. He abandoned it continuously fearing it might become obligatory for the Ummah, as Imam Bukhari (رحمه الله) narrated it.
[Hadith: 1129]

When the Prophet (صلى الله عليه وسلم) passed away and the sequence of revelation ended, the fear of it becoming obligatory was lifted. Thus, Umar (رضي الله عنه) gathered people for the Taraweeh prayer and said regarding it, "What a good innovation this is."
[Bukhari: 2010]

Here, the word "innovation" is used in its linguistic sense, not in its Shar'i (Islamic legal) sense.

The Difference Between Linguistic "Bid'ah" (Innovation) and Shar'i "Bid'ah" (Religious Innovation)​

Linguistic meanings are generally broader than Shar'i meanings, with Shar'i meanings being part of the linguistic meanings. Terms like Taqwa, Siyam (fasting), Hajj, Umrah, and Bid'ah (innovation) are examples. Linguistically, Taqwa means placing something between oneself and what one fears as a shield, such as building houses or pitching tents to protect from the sun's heat and cold. In the Shar'i context, Taqwa means placing something between oneself and Allah's anger to protect from it by fulfilling His commands and avoiding His prohibitions.

Linguistically, Siyam means to refrain. In Shar'i terms, it means to refrain from eating, drinking, and other nullifiers of fasting from dawn to sunset. Linguistically, Hajj means to intend or aim, while in Shar'i terms, it means intending to perform specific rites in Makkah. Linguistically, Umrah means any visitation, but in Shar'i terms, it refers to visiting the Kaaba, performing Tawaf, Sa'i between Safa and Marwah, and shaving or cutting the hair. Similarly, in language, Bid'ah means any newly created thing without a precedent. In Shar'i terms, it refers to any act or belief that has no basis in religion and is contrary to the Sunnah.

Masalih Mursalah (Unrestricted Benefits) Are Not Innovations​

Masalih Mursalah refers to benefits that are not explicitly addressed by any Shar'i evidence, either affirming or negating them, but fulfill a Shar'i purpose. Examples include the compilation of the Quran during the caliphates of Abu Bakr and Uthman (رضي الله عنهما), writing books, and keeping records of those receiving stipends from the public treasury. There is no specific text in Shariah to establish or prohibit these actions. The compilation of the Quran was a means to preserve it, ensuring none of it was lost, fulfilling Allah's promise:

"Indeed, it is We who sent down the Quran and indeed, We will be its guardian."
[Al-Hijr: 9]

When Umar (رضي الله عنه) proposed the idea to Abu Bakr (رضي الله عنه), he hesitated, saying, "How can I do something the Messenger of Allah (صلى الله عليه وسلم) did not do?" Umar (رضي الله عنه) replied, "By Allah, it is better." Abu Bakr (رضي الله عنه) said, "Umar kept urging me until Allah opened my heart to it, and I agreed with him."
[Bukhari: 4679]

Abu Bakr (رضي الله عنه) compiled it into sheets, while Uthman (رضي الله عنه) compiled it into one mushaf. The preparation of registers and records began during Umar's (رضي الله عنه) time. When conquests increased, abundant wealth from spoils and fey (war booty) filled the public treasury, necessitating keeping records of those entitled to stipends to ensure proper distribution and prevent anyone from being deprived. This system did not exist before Umar's (رضي الله عنه) time. Such actions are means to fulfill Shari' objectives and ensure rights are given to those entitled to them, preventing deprivation.

Thus, it cannot be said that some innovations can be considered good by including them in Masalih Mursalah because Masalih Mursalah fulfills Shari' purposes, while innovations imply the Shari'ah is incomplete, as mentioned by Imam Malik (رحمه الله).

Good Intentions Must Align with the Sunnah​

It may be argued by those who trivialize the matter of innovations that a person who commits an innovation to seek closeness to Allah has good intentions. Therefore, his actions should also be considered good based on his intentions. However, the response to this is that while having a noble purpose is important, it is equally essential that the action aligns with the Sunnah. This alignment is one of the two conditions for the acceptance of righteous deeds, which have already been mentioned. These two conditions are sincerity for Allah and obedience to the Messenger of Allah (صلى الله عليه وسلم).

The previously mentioned Hadith confirms that newly invented innovations are rejected by Allah (they do not attain the honor of acceptance). In an agreed-upon Hadith, the Messenger of Allah (صلى الله عليه وسلم) said:

"Whoever introduces into our matter (religion) something that is not from it, it will be rejected."
[Bukhari: 2697, Muslim: 1718]

In the wording of Sahih Muslim, it is stated:

"Whoever does an act which is not in accordance with our matter (religion), it will be rejected."
[Sahih Muslim: 1718/18]

Among the evidences that a noble purpose must be accompanied by adherence to the Sunnah is the story of the Companion who slaughtered his sacrificial animal before the Eid prayer. The Prophet (صلى الله عليه وسلم) said:

"Your sheep is just meat (i.e., it is not counted as a sacrifice)."
[Bukhari: 955, Muslim: 1961]

Commenting on this Hadith, Hafiz Ibn Hajar (رحمه الله) wrote in Fath al-Bari (10/17):

"Sheikh Abu Muhammad bin Abi Hamzah stated that this Hadith proves that an act, even if done with good intentions, is not correct unless it aligns with the way prescribed by Shariah."

This is also evidenced by the incident mentioned with a sound chain in Sunan Darimi (210):

Abdullah bin Mas'ud (رضي الله عنه) saw people in a circle in the mosque, with pebbles in their hands. One of them would say, "Say Allahu Akbar a hundred times," and they would count on the pebbles and say Allahu Akbar a hundred times. Then he would say, "Say La ilaha illa Allah a hundred times," and they would do so. He said, "Say Subhan Allah a hundred times," and they did so. Abdullah bin Mas'ud (رضي الله عنه) stood by them and said: "What is this I see you doing?" They said: "Abu Abdur-Rahman, these are pebbles we use to count takbir, tahleel, and tasbeeh." He replied: "Count your sins; I guarantee that none of your good deeds will be lost. O Ummah of Muhammad (صلى الله عليه وسلم), how quickly you have fallen into destruction. Here are your Prophet's companions available in large numbers. The Prophet's clothes have not yet worn out, and his utensils have not broken. By Him in Whose hand my soul is, either you are upon a religion more guided than the religion of Muhammad (صلى الله عليه وسلم), or you are opening a door of misguidance." They said: "Abu Abdur-Rahman, we intended nothing but good." He replied: "How many people intend good but never attain it."
[Refer to Al-Silsilah al-Saheehah by Shaykh Albani, Hadith: 2005]

The chain of this narration is Hasan.

The Dangers of Innovations and Their Severity Compared to Sins​

The matter of innovations is severe and its consequences are significant. Innovations have widespread harmful effects and are more dangerous than ordinary sins and disobedience. This is because a person committing a regular sin knows and acknowledges that he is engaging in something prohibited and may eventually repent and abandon it. However, an innovator believes he is on the right path, which causes him to persist in his innovation until death, while he is actually following his desires and deviating from the true path. Allah (سبحانه وتعالى) says:

"Is he whose evil deed is made attractive to him so that he considers it good (like one rightly guided)? Verily, Allah sends astray whom He wills and guides whom He wills."
[Faatir: 8]

He also says:

"Is he who stands upon a clear proof from his Lord like one to whom the evil of his conduct is made attractive and they follow their desires?"
[Muhammad: 14]

And He says:

"And do not follow your desire for it will mislead you from the way of Allah."
[Saad: 26]

He also says:

"And who is more astray than one who follows his desire without guidance from Allah?"
[Al-Qasas: 50]

Anas (رضي الله عنه) narrated that the Messenger of Allah (صلى الله عليه وسلم) said:

"Indeed, Allah has blocked repentance from every adherent of innovation until he abandons his innovation."

This Hadith was mentioned by Mundhiri in Al-Targheeb wal-Tarheeb (86) under the section of warnings against abandoning the Sunnah and committing innovations and following desires. He said that it was narrated by Tabarani, and its chain is Hasan. Also refer to [Al-Silsilah al-Saheehah by Shaykh Albani: 1620].

This Hadith is weak due to the Tadlis of Humaid al-Tawil.

The Necessity of Following the Sunnah and Avoiding Innovations​

Multiple hadiths of the Prophet Muhammad (صلى الله عليه وسلم) emphasize the importance of adhering to the Sunnah and caution against innovations, highlighting their dangers. Here are a few:

1. The Prophet's Statement:​

"Whoever introduces into our matter (religion) something that is not from it, it will be rejected."
[Bukhari: 2697, Muslim: 1718]

In another narration in Sahih Muslim, it is stated:

"Whoever does an act which is not in accordance with our matter (religion), it will be rejected."
[Muslim: 1718]

This second narration from Sahih Muslim is more general in meaning as it includes both the one who innovates and the one who acts upon the innovation.

This Hadith is evidence of the obligation to follow the Messenger (صلى الله عليه وسلم) for the acceptance of deeds. Any act intended to seek closeness to Allah is not accepted unless it meets two conditions: complete sincerity for Allah, which aligns with the testimony that there is no deity but Allah, and perfect adherence to the Messenger of Allah (صلى الله عليه وسلم), fulfilling the testimony that Muhammad (صلى الله عليه وسلم) is His Messenger.

Sheikh al-Islam Ibn Taymiyyah (رحمه الله) mentioned in Majmoo' al-Fatawa [18/250] that Fudayl bin Iyad (رحمه الله) explained the verse:

"That He may test you as to which of you is best in deed."
[Al-Mulk: 2]

by saying: "It means the most sincere and the most correct."

If the deed is sincere but not correct, it is not accepted, and if it is correct but not sincere, it is also not accepted. It is only accepted when it is both sincere and correct. Sincere means it is for Allah, and correct means it is in accordance with the Sunnah.

Ibn Kathir (رحمه الله) explained the verse:

"So whoever hopes for the meeting with his Lord, let him do righteous work and not associate anyone in the worship of his Lord."
[Al-Kahf: 110]

saying: "Righteous work is that which is in accordance with the prescribed way of Allah, and free from any form of association with others in worship."
[Tafsir Ibn Kathir, verified by Abdul-Razzaq al-Mahdi, 4/452]

2. The Hadith of Irbad bin Sariyah:​

"The Messenger of Allah (صلى الله عليه وسلم) gave us a sermon which caused our eyes to shed tears and our hearts to tremble. A man said, 'O Messenger of Allah, it is as if this is a farewell sermon. So what do you enjoin upon us?' He said, 'I enjoin you to fear Allah and to listen and obey, even if an Abyssinian slave is appointed as your leader. For whoever among you lives will see great differences, so adhere to my Sunnah and the Sunnah of the rightly guided caliphs. Bite onto it with your molar teeth. Beware of newly invented matters, for every newly invented matter is an innovation, and every innovation is misguidance.'"
[Abu Dawood: 4607, Tirmidhi: 2676, Ibn Majah: 43-44, Tirmidhi said it is "Hasan Sahih"]

The Prophet (صلى الله عليه وسلم) warned of upcoming differences and guided the way to avoid them by following his Sunnah and that of the rightly guided caliphs, and by avoiding innovations.

3. Imam Muslim Narrated from Jabir bin Abdullah (رضي الله عنه):​

"The Messenger of Allah (صلى الله عليه وسلم) used to deliver the Friday sermon by praising Allah and then saying: 'The best speech is the Book of Allah, and the best guidance is the guidance of Muhammad (صلى الله عليه وسلم). The worst of matters are those that are newly invented, and every innovation is misguidance.'"
[Sahih Muslim: 867]

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4. The Prophet's Statement:​

"Whoever turns away from my Sunnah is not from me."
[Bukhari: 5063, Muslim: 1401]

​

5. The Prophet's Statement:​

"O people! I am leaving among you something that if you hold fast to, you will never go astray: the Book of Allah and my Sunnah."
[Al-Hakim 1/93, Hadith 318; see also "Al-Hadith" 14, p. 40]

In the long Hadith narrated by Jabir (رضي الله عنه) regarding the Farewell Pilgrimage, the Prophet (صلى الله عليه وسلم) said:

"I have left among you something that if you hold fast to, you will never go astray: the Book of Allah."
[Sahih Muslim: 1218]

​

6. Imam Bukhari Narrated from Abu Huraira (رضي الله عنه):​

"All of my Ummah will enter Paradise except those who refuse." The people asked, "O Messenger of Allah, who will refuse?" He said, "Whoever obeys me will enter Paradise, and whoever disobeys me has refused."
[Bukhari: 7280]

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7. Imam Bukhari and Imam Muslim Narrated from Abu Huraira (رضي الله عنه):​

"Avoid what I have prohibited and do what I have commanded to the best of your ability. For indeed, the people before you were destroyed because of their excessive questioning and their disagreement with their prophets."
[Bukhari: 7288, Muslim: 1337]

​

8. The Prophet's Statement:​

"None of you truly believes until his desires follow what I have brought."
[Hafiz ibn Hajar in Fath al-Bari (13/289)]

​

9. Imam Bukhari and Imam Muslim Narrated from Umar (رضي الله عنه):​

"Umar came to the Black Stone and kissed it, saying, 'I know that you are a stone and can neither harm nor benefit. If I had not seen the Prophet (صلى الله عليه وسلم) kiss you, I would not have kissed you.'"
[Bukhari: 1597, Muslim: 1270]

​

10. Imam Muslim Narrated from Abu Huraira (رضي الله عنه):​

"Whoever calls to guidance will have a reward similar to those who follow him, without their rewards being diminished. Whoever calls to misguidance will have sin similar to those who follow him, without their sins being diminished."
[Muslim: 2644]

Just as the texts of the Book and Sunnah emphasize following the Sunnah and avoiding innovations, many statements from the early generations of the Ummah (the Sahabah, Tabi'een, and the righteous scholars who followed them) highlight the same principles.

Statements from the Early Generations:​

Abdullah bin Mas'ud (رضي الله عنه) said:

"Follow and do not innovate, for you have been sufficed."
[Darimi: 211]

Uthman bin Hadir (رحمه الله) said:

"I went to Ibn Abbas (رضي الله عنهما) and asked him for advice. He said, 'Cling to the fear of Allah, adhere to the established way, follow, and do not innovate.'"
[Darimi: 141]

Abdullah bin Mas'ud (رضي الله عنه) said:

"Whoever is pleased to meet Allah tomorrow as a Muslim should preserve these prayers where the call is made for them (i.e., in congregation). Allah has prescribed for your Prophet ways of guidance, and these prayers are part of those ways. If you pray them in your houses as this man who stays away from the congregation does, you will have abandoned the Sunnah of your Prophet, and if you abandon the Sunnah of your Prophet, you will go astray."
[Sahih Muslim: 654]

Abdullah bin Umar (رضي الله عنهما) said:

"Every innovation is misguidance, even if people see it as good."
[Al-Sunnah by Al-Marwazi: 82, its chain is authentic]

Muadh bin Jabal (رضي الله عنه) said:

"Beware of newly invented matters, for every innovation is misguidance."
[Abu Dawood: 4611, its chain is authentic]

Umar bin Abdul Aziz (رحمه الله) wrote in a letter:

"I advise you to have the fear of Allah, to adopt moderation in His matter, to follow the Sunnah of His Prophet, and to avoid whatever the innovators have innovated after the Sunnah has been established. It is sufficient for you to adhere to the Sunnah, for it will protect you, by Allah's permission."
[Abu Dawood: 4612]

Sahl bin Abdullah said:

"Whoever introduces a new thing into the knowledge will be asked about it on the Day of Judgment. If it is in accordance with the Sunnah, he will be saved; otherwise, he will not."
[Fath al-Bari 13/290]

Abu Uthman al-Nisaburi said:

"Whoever makes the Sunnah dominant over himself in speech and action, wisdom will flow from his heart and tongue. Whoever allows his desires to dominate over him in speech and action, innovation will appear from his heart and tongue."
[Hilyat al-Awliya: 10/244, its chain is authentic]

Imam Malik (رحمه الله) said:

"Whoever innovates in Islam something he sees as good has claimed that Muhammad (صلى الله عليه وسلم) has betrayed the message. For Allah says: 'This day I have perfected your religion for you.' So whatever was not part of the religion then cannot be part of the religion today."
[Al-I'tisam by Al-Shatibi: 1/28]

Imam Ahmad (رحمه الله) said:

"The principles of the Sunnah with us are: Holding fast to what the Companions of the Messenger of Allah (صلى الله عليه وسلم) were upon, taking them as examples to be followed, avoiding innovations, and every innovation is misguidance."
[Sharh Usul I'tiqad Ahl al-Sunnah by Al-Lalakai: 317]