Sayyiduna al-Bara' bin Azib (may Allah be pleased with him) said: I met my maternal uncle, and he had a banner with him. I asked: Where are you going? He said: "The Messenger of Allah (peace and blessings be upon him) has sent me to a man who has married his father's wife after him, so that I may strike off his neck and kill him."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3394