Musannaf Ibn Abi Shayba 21:165

Waki’ narrated to us, from Isma’il bin ‘Abd al-Malik, from ‘Abdullah bin ‘Ubayd bin ‘Umayr, from ‘Ubayd bin ‘Umayr, that he used to say when he entered the morning and the evening: "O Allah, I ask You, at the presence of Your prayer and the standing of Your callers, that You forgive me and have mercy upon me."