Musnad Ahmad 658:84

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Jabir, who said: I heard al-Sha'bi narrating from al-Bara' ibn 'Azib, from the Prophet, may Allah bless him and grant him peace, that he said regarding his son Ibrahim: "Indeed, he has a wet nurse who suckles him in Paradise."