The Prophet ﷺ said, "Whoever builds a mosque for the sake of Allah, Allah will build for him in Paradise a house more spacious than it."
حدثنا عفان حدثنا عبد الواحد بن زياد عن الحجاج
عن النبي ﷺ قال من بنى لله مسجدا بني له بيت أوسع منه في الجنة
Its isnad is sahih. Hajjaj is Ibn Artah, and the hadith is in Majma al-Zawaid 2:7, where it says, Ahmad narrated it, and it contains Hajjaj bin Artah, who has been criticized. See 2157.His saying "a house was built for him" is how it appears in the three original manuscripts. In Majma al-Zawaid it reads "Allah built a house for him," which conflicts with what is in the original manuscripts of the Musnad. I fear this may be an alteration made by its printer.