Musnad Ahmad 25:481

'Abd al-Wahhab al-Khaffaf narrated to us, he said: Muhammad ibn al-Zubayr informed us, from 'Ali ibn 'Abd Allah ibn 'Abbas, from Ibn 'Abbas, from the Prophet, peace and blessings of Allah be upon him: "A roasted shoulder [of meat] was brought to him, so he ate some morsels from it, then he prayed and did not perform ablution because of that."