From Sahih Muslim (Hadith 1190):
Mahmud b. Labid reported:When 'Uthman b. 'Affan intended to build the mosque (of the Prophet) the people did not approve of it. They liked that it should be kept in the same state. Thereupon he said: I heard the Messenger of Allah (ﷺ) say: He who built a mosque for Allah, Allah would build a house for him like it in Paradise
Reference: Muslim 1190