From Sahih Muslim (Hadith 5959):
Abu Huraira reported Allah's Messenger (ﷺ) as saying:The similitude of mine and that of the Apostles (before me) is that of a person who constructed a building and he built it fine and well and the people went round it saying: Never have we seen a building more imposing than this. but for one brick, and I am that brick (with which you give the finishing touch to the building)
Reference: Muslim 5959