Musannaf Ibn Abi Shayba 19:495

Abu Bakr narrated to us, he said: Shareek narrated to us, from Simak, from Abu Ubayd ibn al-Abras, that Ali was distributing weapons in al-Rahba. A man took a helmet and wrapped it around himself. A man found him and brought him to Ali. He did not cut his hand [for theft], and he said regarding him: "There is a partnership in it."