I heard the Messenger of Allah ﷺ say: ʿWhoever builds a mosque for the sake of Allah, may He be glorified and exalted. Allah will build something like it for him in Paradise.” (Using translation from Aḥmad 434)
سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ مَنْ بَنَى مَسْجِدًا يُصَلَّى فِيهِ بَنَى الله ﷻ لَهُ فِي الْجَنَّةِ أَفْضَلَ مِنْهُ