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 intending to go?” He replied, “The Noble Prophet (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.” So he did exactly that.
Hadith Referenceمسند احمد / أول مسند الكوفيين / 18610