The ruling on changing the beneficiary of a waqf (endowment) from da'wah (calling others to Islam) to something else

Question:
Honorable Shaykh, may Allah grant you success. This questioner says: My grandmother passed away (may Allah have mercy on her) and she established a waqf (endowment) on a property, designating the income from this waqf for da'wah (calling others to Islam) within the Kingdom. His question is: Is it permissible for me to spend this income on needy students of knowledge, or to use it for printing books of Islamic jurisprudence?

Answer:
What changes the waqf (endowment) from its lawful beneficiary? Allah the Exalted said: Therefore, this is not permissible as long as it is in accordance with the Shari'ah (Islamic sacred law) and the Book and the Sunnah, and it is not changed. For this reason, they say: "The wording of the endower is like the wording of the Lawgiver." This means that it is obligatory to implement it and act upon it, and it is not to be changed as long as it does not contradict the Book and the Sunnah. Yes.