Allah, the brother of Abu Al-Qu'ais asked my permission to enter after the verses of Al-Hijab (veiling the ladies) was revealed, and I said, "By Allah, I will not admit him unless I take permission of Allah's Apostle for it was not the brother of Al-Qu'ais who had suckled me, but it was the wife of Al-Qu'ais, who had suckled me." Then Messenger of Allah ﷺ entered upon me, and I said, "O Messenger of Allah ﷺ! The man has not nursed me but his wife has nursed me." He said, "Admit him because he is your uncle (not from blood relation, but because you have been nursed by his wife), Taribat Yaminuki." ʿUrwa said, "Because of this reason, ' Aisha used to say: Foster suckling relations render all those things (marriages etc.) illegal which are illegal because of the corresponding blood relations." (See Hadith No. 36, Vol. 7)  

إِنَّ أَفْلَحَ أَخَا أَبِي الْقُعَيْسِ اسْتَأْذَنَ عَلَىَّ بَعْدَ مَا نَزَلَ الْحِجَابُ فَقُلْتُ وَاللَّهِ لاَ آذَنُ لَهُ حَتَّى أَسْتَأْذِنَ رَسُولَ اللَّهِ ﷺ فَإِنَّ أَخَا أَبِي الْقُعَيْسِ لَيْسَ هُوَ أَرْضَعَنِي وَلَكِنْ أَرْضَعَتْنِي امْرَأَةُ أَبِي الْقُعَيْسِ فَدَخَلَ عَلَىَّ رَسُولُ اللَّهِ ﷺ فَقُلْتُ يَا رَسُولَ اللَّهِ إِنَّ الرَّجُلَ لَيْسَ هُوَ أَرْضَعَنِي وَلَكِنْ أَرْضَعَتْنِي امْرَأَتُهُ قَالَ ائْذَنِي لَهُ فَإِنَّهُ عَمُّكِ تَرِبَتْ يَمِينُكِ قَالَ عُرْوَةُ فَبِذَلِكَ كَانَتْ عَائِشَةُ تَقُولُ حَرِّمُوا مِنَ الرَّضَاعَةِ مَا يَحْرُمُ مِنَ النَّسَبِ  

The Prophet ﷺ intended to return home after the performance of the Hajj, and he saw Safiya standing at the entrance of her tent, depressed and sad because she got her menses. The Prophet ﷺ said, "Aqra Halqa! --An expression used in the Quraish dialect--"You will detain us." The Prophet ﷺ then asked (her), "Did you perform the Tawaf Al-Ifada on the Day of Sacrifice (10th of Dhul-Hijja)?" She said, "Yes." The Prophet ﷺ said, "Then you can leave (with us).  

أَرَادَ النَّبِيُّ ﷺ أَنْ يَنْفِرَ فَرَأَى صَفِيَّةَ عَلَى باب خِبَائِهَا كَئِيبَةً حَزِينَةً لأَنَّهَا حَاضَتْ فَقَالَ عَقْرَى حَلْقَى لُغَةُ قُرَيْشٍ إِنَّكِ لَحَابِسَتُنَا ثُمَّ قَالَ أَكُنْتِ أَفَضْتِ يَوْمَ النَّحْرِ يَعْنِي الطَّوَافَ قَالَتْ نَعَمْ قَالَ فَانْفِرِي إِذًا