Musnad Ahmad 28:72

Yazid narrated to us, Hammam informed us, from Qatadah, from Ibn Sirin and Muhammad ibn Ubayd, from Abdullah ibn Amr, who said: I was with the Messenger of Allah, peace and blessings of Allah be upon him, when Abu Bakr came and asked for permission [to enter]. He said: "Give him permission, and give him glad tidings of Paradise." Then Umar came and asked for permission. He said: "Give him permission, and give him glad tidings of Paradise." Then Uthman came and asked for permission. He said: "Give him permission, and give him glad tidings of Paradise." He [Abdullah ibn Amr] said: I said: "And where am I?" He said: "You are with your father."