Musannaf Ibn Abi Shayba 21:114

Abu Usama narrated to us, from Mis'ar, from 'Asim, who said: Abu Wa'il used to say while he was prostrating: "O Lord, if You pardon me, You pardon me out of Your grace, and if You punish me, You punish me without being unjust and without being preceded (by anyone)." Then he would weep.