Sahih al-Bukhari Book 45, Hadith 12
While I as in the company of Salman bin Rabi`a and Suhan, in one of the holy battles, I found a whip.
One of them told me to drop it but I refused to do so and said that I would give it to its owner if I
found him, otherwise I would utilize it. On our return we performed Hajj and on passing by Medina, I
asked Ubai bin Ka`b about it. He said, "I found a bag containing a hundred Dinars in the lifetime of
the Prophet (ﷺ) and took it to the Prophet (ﷺ) who said to me, 'Make public announcement about it for one
year.' So, I announced it for one year and went to the Prophet (ﷺ) who said, 'Announce it publicly for
another year.' So, I announced it for another year. I went to him again and he said, "Announce for an
other year." So I announced for still another year. I went to the Prophet (ﷺ) for the fourth time, and he
said, 'Remember the amount of money, the description of its container and the string it is tied with,
and if the owner comes, give it to him; otherwise, utilize it.' "
A man asked Allah's Messenger (ﷺ) about the Luqata. He said, "Make public announcement of it for one year, then remember the description of its container and the string it is tied with, utilize the money, and if its owner comes back after that, give it to him." The people asked, "O Allah's Messenger (ﷺ)! What about a lost sheep?" Allah's Messenger (ﷺ) said, "Take it, for it is for you, for your brother, or for the wolf." The man asked, "O Allah's Messenger (ﷺ)! What about a lost camel?" Allah's Messenger (ﷺ) got angry and his cheeks or face became red, and said, "You have no concern with it as it has its feet, and its watercontainer, till its owner finds it."
the above narration (Hadith 616) from Ubai bin Ka`b: adding, "I met the sub-narrator at Mecca later on, but he did not remember whether Ka`b had announced what he had found one year or three years."