question #1 Sahih Muslim 533a, Book 5, Hadith 29 : What are the spiritual benefits of building a mosque for the sake of Allah?

‘Uthman b. ‘Affan listened to the opinion of the people (which was not favourable) when he rebuilt the mosque of the Messenger of Allah (ﷺ). Thereupon he said: You have not been fair to me for I have heard from the Messenger of Allah (ﷺ) saying: He who built a mosque for Allah, the Exalted, Allah would build for him a house in Paradise. Bukair said: I think he (the Holy Prophet) said: While he seeks the pleasure of Allah (by building the mosque). And in the narration of Ibn ‘Isa (the words are):” (a house) like that (mosque) in Paradise.”