The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fada'il Al-Sahabah)
Muslim :: Book 31 : Hadith 6030
Hammam said: I said to Anas b. Malik: Who collected the Qur'an during the lifetime of Allah's Messenger (may peace be upon him)? He said: Four (persons), all of them belonging to Ansir: Ubayy b. Ka'b, Mu'adh b. Jabal, Zaid b. Thabit and a person from the Ansar whose Kunya was Abu Zaid.