Yazid bin Zari' يزيد بن زريع · The Book of Fighting [The Prohibition of Bloodshed]

"I said: 'O Messenger of Allah, which sin is most grievous?' He said: 'Setting up a rival to Allah while it is He that created you.' I said: 'Then what?' He said: 'Killing your child so that he will not eat with you.' I said: 'Then what?' He said: 'Committing adultery with your neighbor's wife.'"

"I heard the Messenger of Allah ) when they are all united, strike him with the sword.'"

A similar report was narrated from 'Abdul-A'la.

"I heard the Messenger of Allah say: 'It is not permissible to shed the blood of a Muslim except in three cases: A man who commits adultery after having married; or one who kills another person, who is to be killed; or who reverts to Kufr after having accepted Islam, who is to be killed.'"

"On the day of the Conquest of Makkah, the Messenger of Allah . He ('Uthman) said: 'O Messenger of Allah! Accept the allegiance of 'Abdullah.' He raised his head and looked at him three times, refusing his allegiance each time, then he accepted his allegiance after three times. Then he turned to his Companions and said: 'Was there not any sensible man among you who would get up when he saw me refusing to give him my hand and kill…