مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 697
Prayer
Mosques and places of Prayer - Section 1
وَعَنْ عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صلى الله عَلَيْهِ وَسَلَّمَ: «مَنْ بَنَى لِلَّهِ مَسْجِدًا بَنَى اللَّهُ لَهُ بَيْتًا فِي الْجَنَّةِ»
‘Uthman reported God's Messenger as saying, “If anyone builds a mosque for God, God will build a house for him in paradise.” (Bukhari and Muslim.)
Mishkat al-Masabih, 697مُتَّفَقٌ عَلَيْهِ (الألباني)