Whoever builds a house for Allah, Allah will build a house for him in Paradise
Mahmud ibn Labid (RAA) reported that Uthman ibn ‘Affan (RAA) decided to rebuild the Mosque (of Allah’s Messenger in Medina) but the people did not like this idea and they wished that it should be preserved in the original form. So Uthman said: I heard the Messenger of Allah (PBUH) say: ‚He who builds a mosque for Allah, Allah would build for him (a house) in Paradise like it.‛ [Sahih Muslim, Book 042, Number 7110]
ك َعنْ َمحْ مُو ِد ب َ ِج ِد َف َك ِر َه ال َّناسُ َذل َ ان ب َْن َع َّف َ أَنَّ ع ُْث َم،ٍْن َل ِبيد ِ ْ أَ َرادَ ِب َنا َء ْال َمس،ان ِ ُ َْوأَ َحبُّوا أَنْ َيدَ َع ُه َع َلى َه ْي َئ ِت ِه َف َقا َل َس ِمع ” َّللا صلى َّللا عليه وسلم َيقُو ُل ِ َّ ت َرسُو َل َلِل َب َنى ه ” َّللاُ َل ُه فِي ا ْل َج هن ِة ِم ْث َل ُه ِ َمنْ َب َنى َم ْس ِجدًا ِ ه