My father رحمه الله narrated to us. He said: Muhammad b. Yahya al-`Attar narrated to us from Muhammad b. Ahmad b. Yahya b. `Imran al-Ash`ari from Sahl b. Ziyad from Ja`far b. Muhammad b. Bashar from `Ubaydullah b. `Abdullah al-Dahqan from `Abd al-Hamid b. Abi'l Daylam from Musa b. Ja`far from his father from his forefathers عليه السلام. He said: The Messenger of Allah صلى الله عليه وعلى آله وسلم said: Whomever sweeps up a mosque on Thursday on the eve of Friday, and a speck of dust comes into his eye, he is forgiven.