Which is the best organ to donate after death to receive a great reward, and how great is this reward? Is it an ongoing charity (Sadaqah Jariyah)? What is the religious ruling on organ donation? Is it permissible for the donor to stipulate which organs are to be donated? And is the donor sinful if these organs are used in unlawful ways?

The best organs for a person to donate are those that offer the greatest benefit and have the most profound impact, while the determination of reward is divinely ordained (tawqifi). Organ donation is permissible, and it is permissible to bequeath them. The donor incurs no sin if the recipient uses the organ for an unlawful purpose, as the aspect of benefit (maslaha) outweighs it.