The Messenger of Allah ﷺ was asked about lost property. He said, "Whatever is found on a frequented road or in an inhabited village, announce it for one year. If its owner comes, give it to him, otherwise it is yours. As for what is not found on a frequented road or in an inhabited village, on it and on buried treasure is the fifth."
أخبرنا قتيبة قال حدثنا أبو عوانة عن عبيد الله بن الأخنس
سئل رسول الله ﷺ عن اللقطة فقال ما كان في طريق مأتي أو في قرية عامرة فعرفها سنة فإن جاء صاحبها وإلا فلك وما لم يكن في طريق مأتي ولا في قرية عامرة ففيه وفي الركاز الخمس
[Its isnad is hasan] Reported by Abu Dawud, Luqata, chapter, "Recognizing found property," h: 1712, from the hadith of Abu Awana al-Wadhah, with this wording. It is also in al-Kubra: 2273. See the hadith that follows at number, h: 4961. This is a portion of it.