Musnad Ahmad 33:187

Sufyan narrated to us, I heard Ibn al-Munkadir say more than once, from Jabir—and it is as if I heard him say: "He informed me who heard Jabir"—so I thought he heard it from Ibn ‘Aqil. Ibn al-Munkadir and ‘Abdullah ibn Muhammad ibn ‘Aqil, from Jabir, that the Prophet (peace and blessings of Allah be upon him) ate meat, then prayed and did not perform ablution. And that Abu Bakr ate *laba’* (beestings/colostrum), then prayed and did not perform ablution. And that ‘Umar ate meat, then prayed and did not perform ablution.