Musannaf Ibn Abi Shayba 13:1680

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Sufyan narrated to us, from Salamah ibn Kuhayl, from Suwayd ibn Ghafalah, who said: I went out, and with me were Zayd ibn Sawhan and Salman ibn Rabi’ah, until when we were at al-‘Udhayb, I picked up a whip. They both said to me: "Throw it away," but I refused. When I came to Medina, I went to Ubayy ibn Ka’b and asked him. He said: "I picked up one hundred dinars during the time of the Prophet, may Allah bless him and grant him peace, and I mentioned that to him. He said: 'Announce it for a year. If its owner comes, then give it to him; otherwise, know its number, its container, and its tie, then it shall be like your own property.'"