Musnad Abu Ya'la al-Mawsili 128:26

Ishaq ibn Abi Isra'il narrated to us, Ya'la ibn 'Ubayd ibn Abi Umayyah narrated to us, Mis'ar narrated to us, from 'Amr ibn 'Amir, who said: I heard Anas saying: The Messenger of Allah (may Allah bless him and grant him peace) was cupped, and he would not withhold anyone's wage.