Musannaf Ibn Abi Shayba 18:550

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Muhammad ibn Qays, from al-Sha’bi, regarding a man who struck his wife’s abdomen and she miscarried. He said: "Upon him is a *ghurra* (compensation for a fetus), which her [the wife's] mother inherits."