All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Zayd ibn Khaalid narrated that: “A man came to the Prophet, sallallaahu ‘alayhi wa sallam, and asked him about found property. The Prophet, sallallaahu ‘alayhi wa sallam, said, ‘Know well the description of its container and the string it is tied with, and make a public announcement about it for one year. If the owner shows up, give it to him; otherwise, do whatever you like with it.’” [Al-Bukhari]
Consequently, you are not permitted to dispose of this property, or a part of it, except after a year of making public announcement in the Masjid, the neighborhood and the market. If the owner did not show up after a year, you are permitted to own it and dispose of it as you wish. If the owner showed up after that, you guarantee the fallen property. Some scholars are of the view that the property should be given in charity on behalf of its owner. If the owner showed up thereafter and approved that behavior, he is rewarded. Otherwise, the person who found it is required to pay it back to the owner and the reward of charity is for him.
We alert that you should not put it in the Masjid if you fear its loss. Rather, you are required to keep it and take the aforementioned steps.
Allaah Knows best.