The Book of Oaths (qasamah), Retaliation and Blood Money
45/39, 40: Chapter
The Diyah For A Woman's Fetus
Sunan an-Nasai
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا حَمَّادٌ، عَنْ عَمْرٍو، عَنْ طَاوُسٍ، أَنَّ عُمَرَ، اسْتَشَارَ النَّاسَ فِي الْجَنِينِ فَقَالَ حَمَلُ بْنُ مَالِكٍ قَضَى رَسُولُ اللَّهِ صلى الله عليه وسلم فِي الْجَنِينِ غُرَّةً . قَالَ طَاوُسٌ إِنَّ الْفَرَسَ غُرَّةٌ .
Hamal bin Malik said: "The Messenger of Allah ruled that a slave (should be given as Diyah) for a fetus." Tawus said: "A horse would do in place of a slave."
Reference : Sunan an-Nasa'i 4816In-book reference : Book 45, Hadith 111English translation : Vol. 5, Book 45, Hadith 4820