Musannaf Ibn Abi Shayba 18:544

Abu Bakr narrated to us, he said: Abd al-Rahim ibn Sulayman narrated to us, from Muhammad ibn Amr, from Abu Salamah, from Abu Hurayrah, that the Messenger of Allah (may Allah bless him and grant him peace) decreed regarding the fetus [killed by a blow] a *ghurra* (compensation) of a male slave or a female slave. The one against whom the blood money was decreed said: "How can we pay for one who did not drink, nor ate, nor cried out, nor made a sound? Such a one is void [of value]." The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, this one speaks with the speech of the poets. In it is a *ghurra* of a male slave or a female slave."