It is narrated from Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him); he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever separates a mother from her child, Allah will separate him from his loved ones on the Day of Resurrection."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 4065