Sunan Ibn Majah 735
سنن ابن ماجه#735Da'ifIt was narrated that 'Umar bin Khattab said:"I heard the Messenger of Allah say: 'Whoever builds a mosque in which the Name of Allah is mentioned, Allah will build a house for him in Paradise
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiDaif
In-book reference: 4:1