The Messenger of Allah ﷺ sent me to a man who had married his father's wife, with orders to strike off his neck and confiscate his property.
بعثني رسول الله ﷺ إلى رجل تزوج امرأة أبيه، أن أضرب عنقه، وأصفي ماله.
It was narrated by Ibn Majah (2608), Daraqutni (3/200), and Bayhaqi (8/208), all of them from the hadith of Abdullah bin Idris, from Khalid bin Abu Kareema, from Muawiya bin Qurra, from his father, and he mentioned it. Its chain is hasan because of Khalid bin Abu Kareema, for he is hasan al-hadith.There has been disagreement over the reason for his killing. It has been said that this is simply the fornication of a married person, so anyone who marries a woman forbidden to him due to kinship is subjected to the penalty for fornication, either stoning or flogging. This is the view of Malik, Shafii, and the two companions of Abu Hanifa, and one report from Imam Ahmad.Abu Hanifa and Sufyan Thawri said, "He is to be disciplined but not flogged."Ahmad said, "He is to be killed in every case and his wealth is to be seized." This is the second report from him, that the Prophet ﷺ simply ordered that he be killed.Perhaps this goes back to his considering it permissible to marry his father's wife according to the custom of the pre-Islamic period. For a man among them used to believe that he had more right to his father's wife than a stranger did, so he would inherit her just as he would inherit his wealth. Whoever does this is an apostate from the religion, so his punishment was death for his apostasy and the seizure of his wealth.