Musnad Abu Ya'la al-Mawsili 110:55

Abu Khaythama narrated to us, Sufyan ibn 'Uyaynah narrated to us, he said: Al-Zuhri narrated to me, from 'Ubayd Allah ibn 'Abd Allah, from Ibn 'Abbas, he said: I and al-Fadl were upon a female donkey, and the Messenger of Allah (may Allah bless him and grant him peace) was praying at 'Arafah. We passed by a part of the row, so we dismounted from it and left it grazing in the row, and the Prophet (may Allah bless him and grant him peace) did not say anything to us.