Musnad Ahmad 26:278

Abu Salamah narrated to us, 'Abd al-'Aziz ibn Muhammad informed us, from 'Amr—meaning Ibn Abi 'Amr—from 'Ubayd Allah ibn 'Abd Allah, from Ibn Mas'ud, who said: I saw the Prophet, peace and blessings of Allah be upon him, eating meat, then he would stand for prayer, and he would not touch a drop of water.