It is narrated from Hazrat Bara’ (may Allah be pleased with him) that one day I met my maternal uncle who had a flag with him. I asked him, "Where are you going?" He replied, "The Prophet Muhammad (peace and blessings be upon him) has sent me to a man who, after his father's death, has married his father's wife (stepmother), and he has commanded me to behead him and seize his wealth."
Hadith Referenceمسند احمد / أول مسند الكوفيين / 18557