Musnad Ahmad 788:2

'Abd al-Samad narrated to us, Hammam narrated to us, Qatadah narrated to us, from Sa'id ibn Abi Burdah and 'Awn ibn 'Utbah, that they witnessed Abu Burdah narrating this hadith to 'Umar ibn 'Abd al-'Aziz. 'Awn said: So he adjured him by Allah, besides whom there is no god, that his father narrated it to him, that he heard it from the Prophet, may Allah bless him and grant him peace. Sa'id did not deny that 'Awn adjured him.