Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: Sayyiduna Umar (may Allah be pleased with him) stood on the pulpit and said: I adjure by Allah any man who heard the judgement of the Messenger of Allah (peace and blessings be upon him) concerning the unborn child. So Haml bin Malik bin al-Nabighah al-Hudhali stood up and said: O Commander of the Believers! I was between two co-wives, and one of them wounded or struck the other with a tent pole, killing her and killing what was in her womb. "The Prophet (peace and blessings be upon him) judged, concerning the unborn child, (compensation of) a male or female slave." So Sayyiduna Umar (may Allah be pleased with him) said: Allahu Akbar! Had we not heard this hadith, we would have judged otherwise.
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3469