Musnad Ahmad 30:2045

Sulayman ibn Dawud narrated to us, he said: Isma'il informed us, from Ibn Dinar—meaning Abdullah—from Abu Salih al-Samman, from Abu Hurayrah, that the Prophet, peace and blessings of Allah be upon him, said: "My likeness and the likeness of the prophets before me is like a man who built a structure, and he perfected it and beautified it, except for the place of a brick in one of its corners. So the people began to walk around it, and they marveled at it, and they said: 'Why was this brick not placed?' He said: 'So I am that brick, and I am the Seal of the Prophets.'"