Becoming Mahram is established by Five Breastfeedings

Sahih Muslim · Book 17 · Hadith 1452 a

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ عَبْدِ اللَّهِ بْنِ أَبِي بَكْرٍ، عَنْ عَمْرَةَ، عَنْ عَائِشَةَ، أَنَّهَا قَالَتْ كَانَ فِيمَا أُنْزِلَ مِنَ الْقُرْآنِ عَشْرُ رَضَعَاتٍ مَعْلُومَاتٍ يُحَرِّمْنَ ‏.‏ ثُمَّ نُسِخْنَ بِخَمْسٍ مَعْلُومَاتٍ فَتُوُفِّيَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَهُنَّ فِيمَا يُقْرَأُ مِنَ الْقُرْآنِ ‏.‏

'A'isha (Allah be pleased with, her) reported that it had been revealed in the Holy Qur'an that ten clear sucklings make the marriage unlawful, then it was abrogated (and substituted) by five sucklings and Allah's Messen…

Sahih Muslim · Book 17 · Hadith 1452 b

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ الْقَعْنَبِيُّ، حَدَّثَنَا سُلَيْمَانُ بْنُ بِلاَلٍ، عَنْ يَحْيَى، - وَهُوَ ابْنُ سَعِيدٍ - عَنْ عَمْرَةَ، أَنَّهَا سَمِعَتْ عَائِشَةَ، تَقُولُ - وَهْىَ تَذْكُرُ الَّذِي يُحَرِّمُ مِنَ الرَّضَاعَةِ - قَالَتْ عَمْرَةُ فَقَالَتْ عَائِشَةُ نَزَلَ فِي الْقُرْآنِ عَشْرُ رَضَعَاتٍ مَعْلُومَاتٍ ثُمَّ نَزَلَ أَيْضًا خَمْسٌ م…

'Amra reported that she heard 'A'isha (Allah he pleased with her) discussing fosterage which (makes marriage) unlawful; and she ('A'isha) said: There was revealed in the Holy Qur'an ten clear sucklings, and then five cle…