Yahya related to me from Malik from Yahya ibn Said that Zayd ibnThabit asked whether it was halal for a man who married a woman andthen separated from her before he had cohabited with her, to marry hermother. Zayd ibn Thabit said, "No. The mother is prohibitedunconditionally. There are conditions, however about foster-mothers." (ES)
USC-MSA web (English) reference: Book 28, Hadith 22 (ES)
Arabic reference (ES): Book 28, Hadith 1116 (ES)