Musnad Abu Ya'la al-Mawsili 108:41

Narrated to us Abd al-A’la, narrated to us Hammad ibn Shu’ayb, from Abu al-Zubayr, from Jabir, from the Prophet (may Allah bless him and grant him peace), who said: "The slaughter of the fetus is the slaughter of its mother, if it has grown hair."