Abu Ja`far Muhammad b. `Ali b. al-Husayn b. Musa b. Babuwayh al-Qummi (rh) narrated to us. He said: My father (ra) narrated to us. He said: Sa`d b. `Abdullah narrated to us from Ahmad b. Abi `Abdullah. He said: Muhammad b. Tasnim narrated to me from al-`Abbas b. `Amer from Ibn Bukayr from Salam b. Ghanim from al-Sadiq Ja`far b. Muhammad from his forefathers (as). The Messenger of Allah (s) said
Whomever sweeps up a mosque, Allah will record the freeing of a slave for him. Whoever comes out of it with something in his eye (a speck of dust), Allah will record double His mercy for him.