Musnad Ahmad 457:31

Muhammad ibn Ja'far narrated to us, he said: Shu'bah narrated to us, from Sulayman, he said: I heard Abu Wa'il narrating from Abu Mas'ud, that a man from his people, who was called Abu Shu'ayb, prepared food. He sent [a message] to the Prophet, peace and blessings of Allah be upon him: "Come to me, you and five [others] with you." He said: So he [the Prophet] sent word to him: "Grant permission for a sixth to join us."