Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) ruled, concerning the penalty for a fetus, "a male slave, or a female slave, or a horse, or a mule."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16416
Tawus (may Allah have mercy on him) says that Sayyiduna Umar (may Allah be pleased with him) sought counsel, then he narrated the full report and said that the Prophet (peace and blessings be upon him) gave a ruling concerning the fetus and the woman, and for the fetus he ruled "a male slave, or a female slave, or a horse."
So he narrated it mursal; and Amr bin Dinar narrated it from Tawus and made it the saying of Tawus himself.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16417
Abdullah bin Buraydah (may Allah have mercy on him) narrates from his father (may Allah be pleased with him) that a woman threw a stone at another and caused her to miscarry, so the Prophet (peace and blessings be upon him) "pronounced the ruling of 500 sheep for the child," and on that day he forbade throwing stones in the future.
In Abu Dawud too 500 is mentioned, but the correct figure is 100 sheep. The Shaykh, the jurist (may Allah have mercy on him), says that there is also a narration about this incident from Abu al-Malih (may Allah be pleased with him) from the Prophet (peace and blessings be upon him), that he (peace and blessings be upon him) "pronounced, concerning the fetus, the penalty of a male slave, or a female slave, or 100 sheep." This is mursal; and there is also a narration from Abu al-Malih (may Allah be pleased with him) with a weak chain that he (peace and blessings be upon him) "pronounced the penalty of a male slave, or a female slave, or 120 sheep."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16419