Is it permissible for a woman to be killed in an honor killing for committing adultery or engaging in an illicit relationship, and what is the evidence for the impermissibility of this without a legitimate trial, and did such incidents occur during the time of the Prophet, may God’s prayers and peace be upon him?

Among the gravest major sins are taking a life and slandering chaste women. Adultery is only proven by the testimony of four men who witness the penetration of the private part into the private part, or by the uncoerced confession of the adulterer or adulteress. The punishment for the adulterer and adulteress is stoning for the married (muḥṣan) and one hundred lashes for the unmarried (ghayr muḥṣan). These punishments are only carried out by those in authority (ūlū al-amr) or their representatives. It is not permissible for the woman's family to kill her, even if she commits adultery. Rather, they must prevent her from evil deeds by confining or restraining her if necessary, as occurred during the time of the Prophet, peace be upon him, with Al-Ghamidiyyah, who committed adultery, and her family did not kill her. Guardians must prevent those under their guardianship from committing indecency and its causes, without leniency or harshness.