He—may Allah Most High have mercy on him—was asked:

“Someone endowed property for the poor. It is part of a group of vineyards whose owners suffer harm because of the endowment. May he revoke it and endow something else instead? If he does so, do both properties become endowments?”

He replied:

“If this causes harm to all the neighbours, it is permissible to exchange it for property that serves the same purpose. The original property then reverts to private ownership, and the replacement becomes an endowment. This is what Umar ibn al-Khattāb, may Allah be pleased with him, did with the mosque of Kufa: when he established another mosque in its place, the original site became a market for date sellers.”

He was also asked:

“A stable was endowed to support a water basin provided for public use. The administrator sold the stable but has purchased nothing with the proceeds for six years. Is this permissible?”

He replied:

“Praise be to Allah. There is no doubt that selling it without acquiring a replacement that serves the same purpose is impermissible. However, if he sold it because it had ceased to be useful and purchased a replacement with the proceeds, this is permissible according to the sounder of the scholars’ two opinions. If he replaces it with something better while it remains useful, the matter is disputed. And Allah knows best.”