It is narrated from Sayyiduna Zayd bin Khalid (may Allah be pleased with him) that a man came to the Prophet (peace and blessings be upon him) and asked him about lost property. He (peace and blessings be upon him) said: "Know its pouch and its tie, then announce it for a year. If its owner comes, give it to him; otherwise it is yours."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12083