There is a large Masjid (mosque) with a large adjacent expanse of land that has been given to it as a Waqf (endowment). We would like to build an Islamic school there to prevent the Muslim children from going to schools established by non-Muslims, Mushriks (those who associate others with Allah in His Divinity or worship), and those who introduces Bid‘ahs (innovations in religion). We will be able to teach students the ‘Aqidah (creed) of Ahl-ul-Sunnah wal-Jama‘ah (those adhering to the Sunnah and the Muslim mainstream) in this school. What is the ruling on constructing a school on this Waqf (endowment) land next to the Masjid?
The Waqf land belonging to this Masjid is a part of it; it is not permissible to change it and use it for a school, as this would change the use of the Waqf to a purpose other than that specified by the donor. However, you can teach the children in the Masjid or the area you mentioned next to the Masjid, without changing the Masjid and its land from its intended use. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.