صحيح البخاري

Narrated Qais bin Abi Hazim:

Abu Bakr went to a lady from the Ahmas tribe called Zainab bint Al-Muhajir and found that she refused to speak. He asked, "Why does she not speak." The people said, "She has intended to perform Hajj without speaking." He said to her, "Speak, for it is illegal not to speak, as it is an action of the pre-islamic period of ignorance. So she spoke and said, "Who are you?" He said, "A man from the Emigrants." She asked, "Which Emigrants?" He replied, "From Quraish." She asked, "From what branch of Quraish are you?" He said, "You ask too many questions; I am Abu Bakr." She said, "How long shall we enjoy this good order (i.e. Islamic religion) which Allah has brought after the period of ignorance?" He said, "You will enjoy it as long as your Imams keep on abiding by its rules and regulations." She asked, "What are the Imams?" He said, "Were there not heads and chiefs of your nation who used to order the people and they used to obey them?" She said, "Yes." He said, "So they (i.e. the Imams) are those whom I meant."