Is it permissible to sell a building we inherited, knowing that our father (may Allah have mercy on him) dedicated the rent of one of its apartments as an endowment (waqf) for his deceased brother's minor children, and how should we deal with the waqf share when distributing the inheritance?

If a man وقف (endows) his apartment for the benefit of his deceased son's minor children, then this waqf must be acted upon. The condition set by the endower is like a text of Sharia (Islamic law); the endowed apartment cannot be inherited, gifted, or sold, and its income should be spent on the endower's grandchildren. If the heirs wish to sell the building, the endowed apartment should not be sold; rather, the other apartments should be sold. It is advisable to refer the matter to the Sharia court to consider the terms of the waqf.