Yahya related to me from Malik from Yazid ibn Abdullah ibn Qusaytal-Laythi that Said ibn al- Musayyab said, "The slaughter of what isin the womb is included in the slaughter of the mother if it isperfectly formed and its hair has begun to grow."
USC-MSA web (English) reference: Book 24, Hadith 9
Arabic reference: Book 24, Hadith 1054