Musnad Abu Ya'la al-Mawsili 160:242

Salih ibn Malik narrated to us, Abd al-A'la ibn Abi al-Masawir narrated to us, Muhammad ibn 'Amr ibn 'Ata' narrated to us, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no Muslim who performs ablution and perfects the ablution, then walks to a house from the houses of Allah to pray in it an obligatory prayer, except that for every step he takes, a good deed is written for him, a bad deed is erased from him by the other, and a degree is raised for him by the other."