Why is it not permissible for us to donate our organs like the heart after death

Answer

In the name of Allah, as long as a person is alive, he has the right to do what he wants of his organs by selling or donating them, only if taking them from his body is not causing his death or his suffering with a fatal disease. Yes, in case if it were before the death of the human and his death is close, like clinically dead, then this transfer is permissible. And know, my son, that if a person dies, his body goes out of his possession; therefore, there is no value of the living person agreeing to transfer the dead's organs to others after death, and it is not permissible for him to ask in his will to donate some of his organs to anyone because the guardianship over the body of the dead is for Imam Mahdi (AJ) only and for the representative in case of absence. Therefore there is no value to the consent of the deceased's heirs. As for after his death, if he is a non-Muslim, it is permissible to transfer from him, while if he is a Muslim it is not permissible unless the life of a Shia Muslim would be saved from inevitable death or something similar to death, with blood money (Diyya) being confirmed for taking the organ from the dead and paid to the awaited Imam (AJ) and not transferred to the heirs of the dead. Allah knows best.