Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) forbade separating a mother from her child. It was said: O Messenger of Allah, until when? He said: "Until the boy reaches puberty and the girl begins to menstruate."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18326