Musannaf Ibn Abi Shayba 20:48

Abu Bakr narrated to us, he said: Mu'tamir ibn Sulayman narrated to us, from Layth, from Tawus, that two co-wives, one of them threw [something] at the other, and she miscarried a fetus. The Messenger of Allah, may Allah bless him and grant him peace, decreed regarding it [the compensation of] a ghurra: a male slave, or a female slave, or a horse.