Sayyiduna al-Bara' bin Azib (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) sent someone to a man who had married his son's wife, to kill him. (Allamah al-Haythami says:) I say:
This is in the Sunan as a hadith of Sayyiduna al-Bara' (may Allah be pleased with him) from his paternal uncle, and from him from his maternal uncle, and from him from Fawaris.
Ahmad recorded it; its narrators are the narrators of the Sahih, except Abu al-Jahm, who is thiqah (trustworthy).
Abu Ya'la also recorded it, and in it he said: He was to strike his neck and bring his head.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الحدود والديات / 10618