It is narrated from Safiyyah bint Abi Ubaid that she informed Nafi‘ that Umm al-Mu’minin Sayyidah Hafsah (may Allah be pleased with her) sent ‘Asim bin ‘Abdullah bin Sa‘d to her sister Fatimah bint ‘Umar to be breastfed ten times so that he could later come to her, and at that time he was a small nursing child. So Fatimah did so, and afterwards he used to come and go to her.
Hadith Referenceمسند الإمام الشافعي / كتاب النكاح / 1181
Hadith Takhrijاسناده صحیح اخرجه البيهقي : 457/7 وفى المعرفة السنن والآثار له (4726) وعبد الرزاق (13929)۔ ومالك في الموطا الرضاع، باب رضاعة الصغير۔