Narrated Ibn Umar:
Allah’s Messenger (ﷺ) said, “A faithful believer remains at liberty regarding his religion unless he kills somebody unlawfully.”
Narrated Abdullah:
A man said, “O Allah’s Messenger (ﷺ)! Which sin is the greatest in Allah’s Sight?” The Prophet (ﷺ) said, “To set up a rival unto Allah though He Alone created you . ” The man said, “What is next?” The Prophet (ﷺ) said, “To kill your son lest he should share your food with you.” The man said, “What is next?” The Prophet said, “To commit illegal sexual intercourse with the wife of your neighbor.” So Allah revealed in confirmation of this narration:– ‘And those who invoke not with Allah, any other god. Nor kill, such life as Allah has forbidden except for just cause nor commit illegal sexual intercourse. And whoever does this shall receive the punishment.’
Narrated Abdullah:
The Prophet (ﷺ) said, “No human being is killed unjustly, but a part of responsibility for the crime is laid on the first son of Adam who invented the tradition of killing (murdering) on the earth.” (It is said that he was Qabil).
Narrated Abdullah:
The Prophet (ﷺ) said, “The first cases to be decided among the people (on the Day of Resurrection) will be those of blood-shed.”
Narrated Abu Zur’a bin Amr bin Jarir:
The Prophet (ﷺ) said during Hajjat-al-Wada`, “Let the people be quiet and listen to me. After me, do not become disbelievers, by striking (cutting) the necks of one another.”
Narrated Abdullah bin Amr:
The Prophet (ﷺ) said, “Al-Ka`ba’ir (the biggest sins) are: To join others (as partners) in worship with Allah, to be undutiful to one’s parents,” or said, “to take a false oath.” (The sub-narrator, Shu`ba is not sure) Mu`adh said: Shu`ba said, “Al-Ka`ba’ir (the biggest sins) are: (1) Joining others as partners in worship with Allah, (2) to take a false oath (3) and to be undutiful to one’s parents,” or said, “to murder (someone unlawfully).
Narrated Ubada bin As-Samat:
I was among those Naqibs (selected leaders) who gave the Pledge of allegiance to Allah’s Messenger (ﷺ). We gave the oath of allegiance, that we would not join partners in worship besides Allah, would not steal, would not commit illegal sexual intercourse, would not kill a life which Allah has forbidden, would not commit robbery, would not disobey (Allah and His Apostle), and if we fulfilled this pledge we would have Paradise, but if we committed any one of these (sins), then our case will be decided by Allah.
Narrated Anas bin Malik:
A girl wearing ornaments, went out at Medina. Somebody struck her with a stone. She was brought to the Prophet (ﷺ) while she was still alive. Allah’s Messenger (ﷺ) asked her, “Did such-and-such a person strike you?” She raised her head, denying that. He asked her a second time, saying, “Did so-and-so strike you?” She raised her head, denying that. He said for the third time, “Did so-and-so strike you?” She lowered her head, agreeing. Allah’s Messenger (ﷺ) then sent for the killer and killed him between two stones.
Narrated Ibn Abbas:
The Prophet (ﷺ) said, “The most hated persons to Allah are three: (1) A person who deviates from the right conduct, i.e., an evil doer, in the Haram (sanctuaries of Mecca and Medina); (2) a person who seeks that the traditions of the Pre-lslamic Period of Ignorance, should remain in Islam (3) and a person who seeks to shed somebody’s blood without any right.”
Narrated Aisha:
“When it was the day of (the battle of) Uhud, the pagans were defeated. Then Satan shouted, “O Allah’s worshipers! Beware of what is behind you!” So the front files attacked the back files of the army. Hudhaifa looked, and behold, there was his father, Al-Yaman (being attacked) ! He shouted (to his companions), “O Allah’s worshipers, my father, my father!” But by Allah, they did not stop till they killed him (i.e., Hudhaifa’s father). Hudhaifa said, “May Allah forgive you.” (`Urwa said, Hudhaifa continued asking Allah’s Forgiveness for the killer of his father till he died.