Muslim

Hadith Commentary: Benefits and Issues:
Fighting against Muslims and raising weapons against them is the action of disbelievers.
Therefore, whoever among the Muslims considers this action permissible and lawful for himself, then he either considers himself or the Muslims to be disbelievers,
thus he will be a disbeliever.
However, if a Muslim, due to some misunderstanding or misinterpretation, or based on ijtihad (independent juristic reasoning), believing it to be a requirement of the religion, commits this act, then he will not be a disbeliever.
And if, unconsciously or without thinking, he does this act for some worldly benefit,
then he has not adopted the attitude and conduct befitting a Muslim,
even though, as a Muslim, he should have adopted the character and conduct of Muslims.
Therefore, he will be considered a criminal and sinful,
but he will not be a disbeliever.

Hadith Commentary:
If someone takes it considering it permissible, then he will be a disbeliever (kafir). And if he does not consider it permissible, then he does not become a disbeliever, but he has done an act like that of the disbelievers. Therefore, it has been stated in an intensified manner that he is not a Muslim, rather he is a disbeliever.

Hadith Commentary:
(1)
What is meant by raising weapons is raising them for the purpose of fighting, because by doing so, the intention is to frighten the believers.
If someone raises weapons for their protection, then they are not included in this warning.

(2)
If someone, considering it permissible for himself, raises weapons against the Muslims, then he is certainly outside the religion of Islam, and the Messenger of Allah (sallallahu alayhi wa sallam) has no connection with him. And whoever does not consider it permissible for himself, he will not be a disbeliever, but he has certainly committed an act similar to that of the disbelievers.
(Fath al-Bari: 12/245)

(3)
The narration of Abu Musa (radi Allahu anhu) has itself been narrated by Imam Bukhari (rahimahullah) with a connected chain.
(Sahih al-Bukhari, al-Fitan, Hadith: 7071)
When raising weapons is such a grave crime, then the gravity of unjustly killing a Muslim is even greater than this.

Urdu Hashiyah (Commentary):

“He is not one of us”—that is, outwardly, because killing Muslims is the act of disbelievers. Furthermore, if he openly goes about killing Muslims, like a bandit or a rebel, then he is included among the combatants (muharibin). However, if, overcome by emotion, he unintentionally commits murder with a weapon, then he will not become a disbeliever; rather, according to the circumstances, the ruling of retribution (qisas) or blood money (diyah) will apply to him. After receiving the punishment, forgiveness is possible because he is a Muslim. And Allah knows best.

Takhrij al-Hadith: [وأخرجه البخاري 7070، ومسلم 98، من حديث مالك به]
Jurisprudential Explanation:
➊ Waging war against the people of faith is a major sin, due to which the assailant is expelled from the group of the people of truth.
➋ This narration from al-Muwatta’ of Ibn al-Qasim is also present in the al-Muwatta’ attributed to Muhammad ibn al-Hasan al-Shaybani [ص370 ح866].
➌ It is forbidden to unjustly raise weapons against a Muslim.
➍ The meaning of "Laysa minna" («ليس علٰي طريقتنا») is: he is not upon our way.
➎ Whoever considers the killing of all Muslims to be lawful is a disbeliever (kafir).
➏ If someone kills a Muslim or Muslims without a valid legal excuse (shar‘i ‘udhr) and without ijtihad, then such a person is a transgressor (fasiq), wicked (fajir), and a grievous sinner.
➐ It is forbidden to frighten a Muslim with a weapon even as a joke.
➑ Due to differences of ijtihad, it is possible for the people of faith to fight among themselves. See: [سورة الحجرات : 9]
➒ Sayyiduna ‘Abdullah ibn ‘Umar radi Allahu anhu said: Whoever says, "Come to prayer," I accept it; and whoever says, "Come to success," I accept it; but whoever says, "Come, let us kill a Muslim brother and seize his wealth," I do not accept it. [طبقات ابن سعد 1/169، 170، حلية الاولياء 1/309 وسنده صحيح]
➓ The religion of Islam is the standard-bearer of peace and security.

Takhrij:
«أخرجه البخاري، الديات، باب قول الله تعالي: " ومن أحياها"، حديث:6874، ومسلم، الإيمان، باب قول النبي صلي الله عليه وسلم من حمل علينا السلاح فليس منا، حديث:98.»©Explanation:
➊ Islam teaches Muslims to live with mutual brotherhood, love, and fraternity; it instructs them in goodwill and compassion towards one another and imparts the lesson of cooperation and mutual support.
➋ According to this hadith, for a Muslim to use weapons against another Muslim is entirely contrary to the teachings of Islam. That is why the Messenger of Allah (sallallahu alayhi wa sallam) said: “Whoever raises a weapon against us has no connection with us.”
➌ The duty of a Muslim is mutual assistance, not fighting. This matter pertains to the rebellious group among the Muslims.
➍ Those who strive to destroy the peace and security of society—according to the Qur’an, fighting should be waged against them until they desist from their rebellious conduct. It is stated in the Noble Qur’an: ﴿ فَقَاتِلُوا الَّتِیْ تَبْغِیْ حَتّٰی تفِيٓئَ اِلٰٓی اَمْرِ اللّٰہِ ﴾ “So fight against the group that transgresses until it returns to the command of Allah.” Numerous ahadith also support this.