The Messenger of Allah ﷺ said, "Whoever builds a mosque for the sake of Allah, even one the size of a sand grouse's nest, Allah will build for him a house in Paradise."
قال رسول الله ﷺ: من بنى الله مسجدا ولو قدر مفحص قطاة، بنى الله له بيتا في الجنة.
Khatib narrated it in Tarikh Baghdad (9/95) from Abu Umar Ibn Mahdi, who said, Muhammad bin Makhlad Attar informed us, Saeed bin Attab narrated to us, Abu Qatada, a shaykh in Basra, narrated to us, Jareer bin Hazim narrated to us, from Amr bin Shuayb, from his father, from his grandfather, who said, and he mentioned the hadith.Abu Qatada, the shaykh in Basra, I have not found a biography for him, except that he has been corroborated. Imam Ahmad narrated it (7056) from Affan, Abdul-Wahid bin Ziyad narrated to us, from Hajjaj bin Artah, from Amr bin Shuayb with his chain, and it contains, "A house wider than it will be built for him in Paradise."Hajjaj bin Artah has been criticized, and he is a mudallis, and here he used the term "an" (indicating a possible break in transmission). With the two chains combined, the hadith rises to the level of hasan, and likewise Amr bin Shuayb's hadith is hasan.As for the wording "wider than it," this is munkar, and Hajjaj bin Artah alone transmitted it, because in the sahih hadiths nothing has come except "like it."