Musannaf Ibn Abi Shayba 35:147

Waki' narrated to us, from Sufyan, from Rabi'ah ibn Abi Abd al-Rahman al-Ra'i, from Yazid, the freed slave of al-Munba'ith, from Zayd ibn Khalid al-Juhani, who said: The Messenger of Allah (may Allah bless him and grant him peace) was asked about a lost item (luqatah). He said: "Make it known for a year. If its owner comes, [give it to him], and if not, then spend it."