The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 1855
Abu Burda b. Abu Musa al-Ash'ari reported: 'Abdullah b. Umar said to me: Did you hear anything from your father narrating something from the messenger of Allah (may peace be upon him) about the time on Friday? I said: Yes, I heard him say from the Messenger of Allah (may peace be upon him) (these words):" It is between the time when the Imam sits down and the end of the prayer."