Can I leave part of my property to a mosque or a tahfiz school in my will?

Yes, as long as the amount does not exceed one third of the estate after debts and funeral costs have been settled. A will (wasiat) for charitable purposes is a deed whose reward keeps flowing. But the family you leave behind is also a priority. The Prophet ﷺ said: “The best charity is the charity from one who has means; and begin with those under your care” (Sahih al-Bukhari 1426). If your family still needs support, a smaller bequest may be wiser. Name the institution precisely, including its address, and state whether it is for waqf or general use. Also inform the mosque or school so they know to claim it later. See waqf and ongoing charity.