Sayyiduna Zayd bin Khalid al-Juhani (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) was asked about lost gold and silver, and the Messenger of Allah (peace and blessings be upon him) said: "Recognise its container and its tie. Then announce it for a year. If it is not recognised, include it in your spending, and it will be a trust with you. If its owner comes at any time, give it to him." He asked about a stray camel, and he (peace and blessings be upon him) said: "What have you to do with it! Leave it, for it has its hooves and its water supply with it; it can go down to water and eat the leaves of trees until its owner finds it." He asked about a sheep, and he (peace and blessings be upon him) said: "Take it, for it is for you, or for your brother, or for the wolf."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12067