ما حكم الكنز الموجود تحت المسجد وكيف يتم توزيعه أو لمن يعود؟

Regarding treasure buried in land endowed for a mosque:

If the owner of the land claims it, then he has a greater right to it, because the sale of the land and its endowment does not include buried treasure. If the endower was unaware of it, then consider: If it dates back to the Islamic era, it is considered a lost item (Luqata) and must be announced for a year. After that, it should be placed in the public treasury (Bayt al-Mal) or spent on the welfare of Muslims, the poor, the needy, students of knowledge, and the interests of mosques. If it dates back to the pre-Islamic era, it is considered a buried treasure (Rikaz), and one-fifth of it must be allocated to the mosque.