Ishaq bin Abdullah (may Allah have mercy on him) narrates from his paternal uncle Anas bin Malik (may Allah be pleased with him) that he said: I prayed behind the Prophet (peace and blessings be upon him), and with me was a child, and Umm Sulaym (may Allah be pleased with her) was behind us.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5220