Musnad Ahmad 33:684

Abu al-Jawwab narrated to us, Ammar ibn Ruzayq narrated to us, from al-A'mash, from Abu Sufyan, from Jabir, who said: There was a man from the Ansar called Abu Shu'ayb, and he had a butcher slave. He said to him: "Prepare food for us, for I might invite the Messenger of Allah (peace and blessings of Allah be upon him) as the sixth of six." So he invited them, but a man followed them. The Messenger of Allah (peace and blessings of Allah be upon him) said to him: "This man has followed us, so do you give him permission?" He said: "Yes."