Mu'awiyah bin Qurrah narrates from his father (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) sent his father, that is, Mu'awiyah's grandfather, to a man who had married his father's wife; he struck off his neck and took the khumus (one-fifth) of his wealth.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12722