Musannaf Ibn Abi Shayba 21:82

Waki’ narrated to us, from Fudayl ibn Marzuq, from ‘Atiyyah, from Abu Sa’id, who said: Whoever says, when he goes out to the prayer: "O Allah, I ask You by the right of those who ask of You, and by the right of this walking of mine, for I have not gone out in arrogance, nor pride, nor showing off, nor for reputation; I have gone out seeking Your pleasure and fearing Your wrath. I ask You to save me from the Fire and to forgive me my sins, for no one forgives sins except You," Allah will turn His Face toward him until he finishes, and He will appoint seventy thousand angels to seek forgiveness for him.