Musnad Ahmad 30:204

"The likeness of the prophets is like a man who built a structure, and he perfected it, completed it, and beautified it. So people began to circle around it, saying: 'We have not seen a building more beautiful than this, except for this gap.' And I am that gap." It was said to Sufyan: "Who mentioned this?" He said: "Abu al-Zinad, from al-A'raj, from Abu Hurayrah."