What do the muftis say about this issue: A person gave a house to the madrasa asking to make a madrasa in it and said “as long as I am alive, you should continue to pay me rent for it, and after my death this house is dedicated as waqf to the madrasa”, and this whole matter was registered. Now the madrasa owners believe that if a mosque is built on this place, people of the neighborhood will benefit more. The question is whether they can build a mosque on this place or not? If they can, after the mosque is built... will it be eligible for rent or not?
Let it be known that the person who gave the house has specifically dedicated it as a waqf to the Madrasa, it is not right to build a mosque in it or use it for any other good purpose. Rather, as long as the person is alive, he/she is entitled to receive the rent of this land, and will be given to him/her, and after his/her death, this house will be considered dedicated waqf to the Madrasa.
کما فی الاشباہ والنظائر: شرط الواقف یجب اتباعھم لقولھم:شرط الواقف کنص الشارع أی فی وجوب العمل به اھ(ص/106)۔
وفی الدر المختار:(وجاز جعل غلة الوقف) أو الولاية (لنفسه عند الثاني) وعليه الفتوى اھ(4/384)۔