Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both), concerning the saying of Allah Almighty: "And do not marry those whom your fathers have married." [Surah al-Nisa: 22]
"And the wives of your sons." [Surah al-Nisa: 23] (said): Every woman whom your father or your son has married, whether he had intercourse with her or not, is forbidden to you.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13912