Al-Hasan said:

The Prophet had commanded Abu Bakr to proclaim the disavowal (Bara'ah) to the people, but when he had departed, he called him back and said: "No one shall convey this matter on my behalf except a man from my own household."

Muhammad [Ibn Abi Zamanin] said: Some scholars said:

The Prophet (peace be upon him) commanded Ali with that instead of Abu Bakr because it was the custom of the Arabs, when breaking their treaties, that this should be undertaken by a man from the tribe itself. It would have been permissible for the Arabs to say: "[Thus] you have broken the treaties from the Messenger, and this is contrary to what we know among ourselves regarding the breaking of treaties." Thus, he (peace be upon him) removed any cause for objection. This took place in the year nine of the Hijrah, one year after the conquest of Mecca.

Muhammad said: Regarding His saying "Bara'ah" (Disavowal), it may be grammatically elevated (marfu') in two ways: One of them is as the predicate of an implied subject, meaning: "These verses are a disavowal from Allah and His Messenger." The other is as the subject (mubtada'), where the predicate would be "except for those with whom you have made a treaty."

His saying: "If you repent," He says to the polytheists: If you repent from polytheism, "then it is better for you; but if you turn away" from Allah and His Messenger, "then know that you will not escape Allah, and give tidings to those who disbelieve of a painful punishment," meaning: killing before the punishment of the Hereafter.