Yahya bin Ya'mar narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) concerning a man who committed zina with his wife's mother or her daughter: he has transgressed two sanctities, but his wife does not become unlawful to him. Yahya bin Ya'mar said: The unlawful never makes the lawful unlawful. This reached al-Sha'bi (may Allah have mercy on him), and he said: Rather, if I took a jug of wine and poured it into a cistern of water, that water would become unlawful. Al-Sha'bi's view was that she does become unlawful to him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13960