It is narrated from Sayyidah Judhamah bint Wahb al-Asadiyyah (may Allah be pleased with her): I heard the Messenger of Allah (peace and blessings be upon him); he (peace and blessings be upon him) said: "I intended to forbid ghilah, until I recalled that the Romans and the Persians do it and it does not harm their children."
Imam Muslim (may Allah have mercy on him) recorded it from Yahya bin Yahya.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرضاع / 15684