Is it permissible, Islamically, for a woman to sell her apartment with the intention of endowing its price as an ongoing charity (ṣadaqah jāriyah), provided that she remains in the apartment under a symbolic rental contract until her death, with the buyer’s knowledge and consent of this arrangement?

There is no objection to a woman selling her apartment during her lifetime, while she is in good health and of sound mind. It is permissible for her to donate some of its price, or to rent out the apartment itself, or to stipulate with the buyer a usufruct of the apartment for a known period, based on the hadith of Jabir concerning stipulating the use of a camel for transport to Medina, and what Ibn Qudamah mentioned regarding the permissibility of stipulating a known benefit in the sold item, or the seller's benefit in the sold item, or for the seller to reserve the usufruct of the sold item for a known period.

However, stipulating her remaining in the apartment for the rest of her life is not permissible due to the unknown duration and the element of gharar (excessive uncertainty), which invalidates the sales contract, as the Prophet (peace be upon him) forbade gharar.

Therefore, she should either sell the apartment for a known price and reserve its usufruct for a known period, or she may bequeath one-third of the apartment after her death to be an endowment (waqf). A bequest exceeding one-third is not effective unless approved by the heirs.