Musnad Ahmad 12:12

'Affan narrated to us, Mu'tamir ibn Sulayman narrated to us, he said: I heard my father saying: Abu 'Uthman narrated to us, that 'Abd al-Rahman ibn Abi Bakr narrated to him, that the People of the Suffah were poor people, and that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever has food for two, let him take a third, and whoever has food for four, let him take a fifth or a sixth," or as he said. And Abu Bakr came with three, and the Prophet of Allah (peace and blessings of Allah be upon him) went with ten. He said: So it was me, my father, and my mother—and I do not know if he said: my wife—and a servant between our house and the house of Abu Bakr (may Allah be pleased with him).