It was narrated from 'Aishah:
that the Prophet entered upon her and there was a man with her. He said: “Who is this? She said: “This is my brother.” He said: “Look at whom you allow to enter upon you, because the breastfeeding (that makes a person Mahram) is that which satisfies hunger.”

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ سُفْيَانَ، عَنْ أَشْعَثَ بْنِ أَبِي الشَّعْثَاءِ، عَنْ أَبِيهِ، عَنْ مَسْرُوقٍ، عَنْ عَائِشَةَ، أَنَّ النَّبِيَّ ﷺ دَخَلَ عَلَيْهَا وَعِنْدَهَا رَجُلٌ فَقَالَ " مَنْ هَذَا " . قَالَتْ هَذَا أَخِي . قَالَ " انْظُرُوا مَنْ تُدْخِلْنَ عَلَيْكُنَّ فَإِنَّ الرَّضَاعَةَ مِنَ الْمَجَاعَةِ " .