Allah Almighty's command is:
إِنَّا نَحْنُ نَزَّلْنَا الذِّكْرَوَإِنَّا لَهُ لَحَافِظُونَ
Reference: (Al-Hijr:9)
Translation: Indeed, We have sent down the Reminder, and indeed, We will be its guardian.
From the mentioned verse, it is understood that Allah Almighty has taken the responsibility of protecting the Holy Quran, and if the Prophetic Hadith were also a proof and evidence like the Holy Quran, then its protection would also have been arranged by Allah Almighty.
① First Point
Allah Almighty has taken the responsibility of protecting the "Reminder," and this protection is not exclusive only to the Holy Quran but the "Reminder" means the religion and Shariah revealed by Allah Almighty. The evidence for this is Allah Almighty's command:
فَاسْأَلُوا أَهْلَ الذِّكْرِ إِنْ كُنْتُمْ لَا تَعْلَمُونَ
Reference: (Surah An-Nahl:43)
Translation: So if you do not know, ask those who possess the Reminder (knowledge).
And there is no doubt that just as Allah Almighty has protected His Book, the Holy Quran, in the same way, He has also arranged for the protection of the Sunnah, and for this, He created such people who learned it and taught it, memorized it, and distinguished between its authentic and weak parts.
② Second Point
Allah Almighty says:
وَأَنْزَلْنَا إِلَيْكَ الذِّكْرَ لِتُبَيِّنَ لِلنَّاسِ مَا نُزِّلَ إِلَيْهِمْ
Reference: (Surah An-Nahl:44)
Translation: This is a reminder We have sent down to you so that you may explain to the people what has been revealed to them.
From this verse, it is understood that the responsibility of the Prophet ﷺ was not only to recite or have the words revealed to him by Allah read out or written down to the people, but also to explain and clarify the meaning and interpretation of what was revealed to him.
So if we accept that Allah Almighty has guaranteed the protection of only the Quran and not the Sunnah, then the benefit of the Quran would remain incomplete, because the Quran itself indicates that its explanation and clarification are still necessary, and this is also the responsibility of the Prophet ﷺ.
③ Third point
Following the Quran without its explanation is impossible, because many of the Quran's commands are mentioned briefly, such as prayer, zakat, Hajj, etc. We do not know the details of these commands except for what the Messenger of Allah ﷺ has informed us through his explanation. So if the hadiths are not preserved, then how will these commands be implemented!
How and when will the prayer be performed, on how much wealth and how much zakat will be paid, and what will be the procedure for Hajj!
④ Fourth Point
The command of the Almighty is:
وَمَا أَنْزَلْنَا عَلَيْكَ الْكِتَابَ إِلاّ لِتُبَيِّنَ لَهُمُ الَّذِي اخْتَلَفُوا فِيهِ وَهُدىً وَرَحْمَةً لِقَوْمٍ يُؤْمِنُونَ
Reference: (Surah An-Nahl:64)
Translation: We have sent down this Book to you so that you may make clear to them that wherein they differ, and it is a guidance and mercy for the believers.
The mentioned verse refers to the mission of the Prophet ﷺ, which was the responsibility of prophethood upon him ﷺ, and that is to explain the Holy Quran and resolve disputes. So, did you fulfill that mission? If yes, and certainly yes, then is that (explanation) preserved or not? If the answer is no, then that explanation is of no benefit, and if the answer is yes, then where is it preserved?! Certainly, it has been preserved in the form of Hadiths and (by the will of Allah Almighty) has reached us.
⑤ Fifth Point
Allah Almighty says:
الْيَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي
Reference: (Surah Al-Ma'idah:3)
Translation: Today I have perfected your religion for you and completed My favor upon you.
If we accept the claim that Allah Almighty did not take responsibility for the preservation of the Sunnah and that it has been mixed with falsehood to the extent that truth and falsehood cannot be distinguished in it!
Then what is the completion of religion for us? Or was this completion only specific to the Companions?!
If this completion was for everyone, then it is necessary that everything the Messenger of Allah ﷺ said about the religion is preserved entirely without any alteration!
⑥ Sixth Point
Allah Almighty preserved the Quran through His servants, and if we study the history of the science of Hadith, we will find that Allah Almighty also preserved the Sunnah in the same way through His servants, who not only dedicated their lives to preserving the Sunnah but also sacrificed their lives and valuable possessions in its defense, which confirms that Allah Almighty has preserved the Sunnah of His Prophet just as He has preserved His Book.
Imam Ibn Rajab, may Allah have mercy on him, says: "Thus, Allah Almighty created certain people to preserve the Prophetic Hadith, who separated falsehood, deception, and incorrect statements from it, and they preserved it with great care."
Reference: Tafsir Ibn Rajab al-Hanbali (1/605)
To see unique efforts and attempts of Hadith scholars in this regard, it would be useful to look at Imam Khateeb Baghdadi’s books "Sharaf As'hab al-Hadith" and "Al-Rihla fi Talab al-Hadith."
⑦ Seventh Point
Here, there are two different things; one is the statement and the other is the explained text. By statement is meant clarification and explanation, and by explained text is meant the text which has been clarified.
And as has been mentioned, the responsibility of explaining the Wise Quran was entrusted to the Prophet ﷺ, so the Quran became the explained text and the sayings of the Prophet ﷺ became its explanation. It is clear that the explanation given by the Prophet ﷺ is not present in the Quran; therefore, it is established that the statement is a thing separate from the explained text, which is the Prophetic Hadith, whose preservation is in fact an essential part of the preservation of the Glorious Quran.
