Musannaf Ibn Abi Shayba 35:148

Waki’ narrated to us, from Sufyan, from Salamah ibn Kuhayl, from Suwayd ibn Ghaflah, who said: I went out with Zayd ibn Suhan 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 we came to Medina, I went to Ubayy ibn Ka’b and asked him. He said: I picked up a hundred dinars during the time of the Prophet, may Allah bless him and grant him peace, and I mentioned that to him. He said: "Make it known for a year." So I made it known for a year, but I did not find anyone who recognized it. I came to him [again], and he said: "Make it known for a year. If you find its owner, then hand it over to him. Otherwise, recognize its number, its container, and its tie, then it shall be like your own property." And it was mentioned that Abu Hanifah said: If its owner comes, he [the finder] must compensate him for it.