Musnad Abu Ya'la al-Mawsili 155:361

'Abd al-Jabbar ibn 'Asim narrated to us, 'Ubayd Allah ibn 'Amr narrated to us, from Zayd ibn Abi Unaysah, from 'Adi ibn Thabit, from Abu Hazim al-Ashja'i, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever purifies himself in his house, then walks to a house from the houses of Allah to perform an obligation from the obligations of Allah, then his two steps—one of them erases a sin, and the other raises a degree."