Hadith 1096B2

وَقَالَ مَالِكٌ فِي الرَّجُلِ يَتَزَوَّجُ الْمَرْأَةَ، ثُمَّ يَنْكِحُ أُمَّهَا، فَيُصِيبُهَا : إِنَّهُ لَا تَحِلُّ لَهُ أُمُّهَا أَبَدًا، وَلَا تَحِلُّ لِأَبِيهِ، وَلَا لِابْنِهِ، وَلَا تَحِلُّ لَهُ ابْنَتُهَا، وَتَحْرُمُ عَلَيْهِ امْرَأَتُهُ
Imam Malik, may Allah have mercy on him, said: However, if he does not have intercourse with the mother, then he should leave her, and her daughter will remain lawful for him.

Imam Malik, may Allah have mercy on him, said: If a man marries a woman, then marries her mother and has intercourse with her, then the mother’s mother will also become unlawful, and the mother will remain unlawful for that man’s father and son.
Hadith Reference موطا امام مالك رواية يحييٰ / كتاب النكاح / 1096B2
Hadith Takhrij «فواد عبدالباقي نمبر: 28 - كِتَابُ النِّكَاحِ-ح: 23»