Musnad Ahmad Hadith 10467

It is narrated from Abu Huraira (may Allah be pleased with him) that the Noble Prophet (ﷺ) said: There was a dispute between two women of the Banu Huzail. One of them struck the other, who was pregnant, with a stone and killed her, and the child in her womb was also born dead. The Noble Prophet (ﷺ) ruled that the family of the killer must pay the blood money (diyah) for the slain woman and, regarding her child, one "ghurra"—that is, a slave man or woman. Upon this decision, a man objected (in rhymed prose), saying: How can the blood money for a child be decided, who neither ate nor drank, nor spoke nor cried? Such things are usually left aside. According to Abu Huraira (may Allah be pleased with him), the Noble Prophet (ﷺ) said: This man is speaking in the manner of poets (in rhymed phrases). Yes, in this case, a "ghurra"—that is, a slave man or woman—is indeed obligatory.