Sahih Muslim , Book 8, Hadith 3397 (USC-MSA) ⓘ

'A'isha (Allah be pleased with her) reported that Aflah, the brother of Abu'l-Qu'ais, who was her uncle by reason of fosterage, came, and asked her permission (to enter the house) after seclusion (Hijab) was instituted. I refused to admit him. When Allah's Messenger came, I informed him what I had done. He commanded me to grant him permission (as the brother of her foster-father was also her uncle).

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ، عَنْ عُرْوَةَ بْنِ الزُّبَيْرِ، عَنْ عَائِشَةَ، أَنَّهَا أَخْبَرَتْهُ أَنَّ أَفْلَحَ - أَخَا أَبِي الْقُعَيْسِ - جَاءَ يَسْتَأْذِنُ عَلَيْهَا وَهُوَ عَمُّهَا مِنَ الرَّضَاعَةِ بَعْدَ أَنْ أُنْزِلَ الْحِجَابُ قَالَتْ فَأَبَيْتُ أَنْ آذَنَ لَهُ فَلَمَّا جَاءَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَخْبَرْتُهُ بِالَّذِي صَنَعْتُ فَأَمَرَنِي أَنْ آذَنَ لَهُ عَلَىَّ ‏.‏