The Messenger of Allah ﷺ said, "Whoever builds a mosque in which Allah is remembered, Allah will build for him a house in Paradise."
قال رسول الله ﷺ: من بنى مسجدا يذكر الله فيه، بنى الله عز وجل له بيتا في الجنة.
Nasai (688) narrated it from Amr bin Uthman, who said, Baqiya narrated to us, from Buhayr, from Khalid bin Madan, from Kathir bin Mura, from Amr bin Abasa, and he mentioned the same. Tirmidhi (1635) also narrated it from Haywa bin Shurayh Al-Himsi, from Baqiya, with the same chain, except that he did not mention the part being cited as evidence, but instead mentioned in it, "Whoever grows grey hair in the path of Allah, it will be a light for him on the Day of Resurrection," and he said, hasan sahih gharib.I say, it is hasan only, for the isnad contains Baqiya bin Walid, who is truthful but practices tadlis al-taswiya, except that here he explicitly stated "narrated to us." Imam Ahmad (19440) said, Haywa bin Shurayh narrated to us, Baqiya narrated to us, Buhayr bin Saad narrated to us, with the same chain, and in it, "Whoever builds a masjid for Allah in order to remember Allah, Mighty and Majestic, in it, Allah will build for him a house in Paradise, and whoever frees a Muslim soul, it will be his ransom from Hellfire, and whoever grows grey hair in the path of Allah it will be a light for him on the Day of Resurrection."