Sahih Bukhari Volume 3, Book 42, Hadith Number 610.
Narated By Sulaiman bin Bilal from Yahya : Yazid Maula Al-Munba’ith heard Zaid bin Khalid al-Juham saying, “The Prophet was asked about Luqata. He said, ‘Remember the description of its container and the string it is tied with, and announce it publicly for one year.’ ” Yazid added, “If nobody claims then the person who has found it can spend it, and it is regarded as a trust entrusted to him.” Yahya said, “I do not know whether the last sentences were said by the Prophet or by Yazid.” Zaid further said, “The Prophet was asked, ‘What about a lost sheep?’ The Prophet said, ‘Take it, for it is for you or for your brother (i.e. its owner) or for the wolf.” Yazid added that it should also be announced publicly. The man then asked the Prophet about a lost camel. The Prophet said, “Leave it, as it has its feet, water container (reservoir), and it will reach a place of water and eat trees till its owner finds it.”