Musnad Abu Ya'la al-Mawsili 1:24

Abu Khaythama narrated to us, Jarrah ibn Makhlad al-Basri Abu Abd Allah narrated to us, Musa ibn Dawud narrated to us, Husam ibn Misak narrated to us, from Muhammad ibn Sirin, from Ibn Abbas, from Abu Bakr: That the Prophet (peace and blessings of Allah be upon him) gnawed on a shoulder [of meat], then prayed and did not perform ablution.