عَنِ ابْنِ عَبَّاسٍ قَالَ: حُرِّمَ مِنَ النَّسَبِ سَبْعٌ وَمِنَ الصِّهْرِ سَبْعٌ ثُمَّ قَرَأَ: (حُرِّمَتْ عَلَيْكُم أُمَّهَاتكُم) الْآيَة. رَوَاهُ البُخَارِيّ

‘Amr b. Shu’aib, on his father’s authority, said that his grandfather reported God’s Messenger as saying, “If any man marries a woman and cohabits with her it is not lawful for him to marry her daughter, but if he does not cohabit with her he may marry her daughter; and if any man marries a woman it is not lawful of him to marry her mother whether he has cohabited with her or not.” Tirmidhi transmitted it, saying this is a tradition which is not sound, with respect to its isnad. It is transmitted only by Ibn Lahi'a and al-Muthanna b. as-Sabbah on the authority of ‘Amr b. Shu’aib, and they are both declared to be weak in tradition.