Musnad Ahmad 658:192

Waki' narrated to us, he said: Shu'bah narrated to us, from 'Adi ibn Thabit, from Al-Bara' ibn 'Azib, who said: When Ibrahim, the son of the Messenger of Allah (peace and blessings of Allah be upon him), died, the Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, he has a wet nurse in Paradise."