Imam Ahmad recorded that Abu Hurayrah, may Allah be pleased with him, said that the Messenger of Allah said:

«إِنَّ مَثَلِي وَمَثَلَ الْأَنْبِيَاءِ مِنْ قَبْلِي كَمَثَلِ رَجُلٍ ابْتَنَى بُيُوتًا فَأَكْمَلَهَا وَأَحْسَنَهَا وَأَجْمَلَهَا إِلَّا مَوْضِعَ لَبِنَةٍ مِنْ زَاوِيَةٍ مِنْ زَوَايَاهَا، فَجَعَلَ النَّاسُ يَطُوفُونَ وَيُعْجِبُهُمُ الْبُنْيَانُ وَيَقُولُونَ: أَلَّا وَضَعْتَ ههُنَا لَبِنَةً فَيَتِمُّ بُنْيَانُك»

(The parable of myself and the Prophets who came before me is that of a man who built houses and made them complete and beautiful apart from the space of a brick in one of the corners. The people started to walk around, admiring the construction and saying, If only you put a brick here, your construction will be complete.) The Messenger of Allah said:

«فَكُنْتُ أَنَا اللَّبِنَة»

(And I am that brick.) It was also recorded by (Al-Bukhari and Muslim).