The Book Pertaining to the Excellent Qualities of the Holy Prophet (may Peace be upon them) and His Companions (Kitab Al-Fada'il)
Muslim :: Book 30 : Hadith 5812
This hadith has been transmitted on the authority of Ma'mar (and the words are): I said to Zuhri: What does (the word) al-'Aqib imply? He said: One after whom there is no Prophet, and in the hadith transmitted on the authority of Ma'mar and 'Uqail there is a slight variation of wording.