كتاب القسامة
Read the English translation first, with the original Arabic directly underneath.
'Amr bin Dinar narrated that:
he heard Tawus narrate from Ibn 'Abbas, from 'Umar, may Allah be pleased with him, that he asked about the ruling of the Messenger of Allah concerning that. Hamal bin Malik stood up and said: "I was married to two women, and one of them struck the other with a tent pole and killed her and her fetus. The Prophet (ﷺ) ruled that a slave be given (as Diyah) for her fetus and that she be killed (for killing the other woman)."
أَخْبَرَنَا يُوسُفُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا حَجَّاجُ بْنُ مُحَمَّدٍ، عَنِ ابْنِ جُرَيْجٍ، قَالَ أَخْبَرَنِي عَمْرُو بْنُ دِينَارٍ، أَنَّهُ سَمِعَ طَاوُسًا، يُحَدِّثُ عَنِ ابْنِ عَبَّاسٍ، عَنْ عُمَرَ، رضى الله عنه أَنَّهُ نَشَدَ قَضَاءَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي ذَلِكَ فَقَامَ حَمَلُ بْنُ مَالِكٍ فَقَالَ كُنْتُ بَيْنَ حُجْرَتَىِ امْرَأَتَيْنِ فَضَرَبَتْ إِحْدَاهُمَا الأُخْرَى بِمِسْطَحٍ فَقَتَلَتْهَا وَجَنِينَهَا فَقَضَى النَّبِيُّ صلى الله عليه وسلم فِي جَنِينِهَا بِغُرَّةٍ وَأَنْ تُقْتَلَ بِهَا .