Adi bin Thabit al-Ansari (may Allah have mercy on him) said that when Abu Qays bin al-Aslat (may Allah be pleased with him) died, his son Qays proposed marriage to his father's wife. She came to the Messenger of Allah (peace and blessings be upon him) and said: O Messenger of Allah, Abu Qays has died, and his son Qays is a good man of the tribe; he has proposed marriage to me. I said to him that I regard you as my son, and that I will first go to the Messenger of Allah (peace and blessings be upon him). The Messenger of Allah (peace and blessings be upon him) remained silent, and this verse was revealed: "And do not marry those women whom your fathers have married." [Surah al-Nisa: 22]
This is mursal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13917
Yazid bin al-Bara' narrates from his father (may Allah be pleased with him) that he said: I met my paternal uncle (may Allah be pleased with him), and he was carrying a banner. I asked: Where are you headed? He said that the Messenger of Allah (peace and blessings be upon him) has sent me: "to a man who has married his father's wife, that I strike off his neck and also take his wealth."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13918