It is narrated from Nafi' (may Allah have mercy on him) that Salim bin Abdullah (may Allah have mercy on him) informed him that Aishah (may Allah be pleased with her), the wife of the Prophet (peace and blessings be upon him), sent him, while he was still a nursing infant, to her sister Umm Kulthum (may Allah be pleased with her). She suckled him three times, then she fell ill, and she did not suckle him more than the three sucklings. (Salim said:) So I would not come in to Aishah (may Allah be pleased with her) because Umm Kulthum (may Allah be pleased with her) did not complete ten sucklings for me, that is, she did not suckle me ten times.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرضاع / 15638