Sunan an-Nasa'i 4795

أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، عَنِ ابْنِ أَبِي عَدِيٍّ، عَنْ خَالِدٍ، عَنِ الْقَاسِمِ، عَنْ عُقْبَةَ بْنِ أَوْسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ أَلاَ إِنَّ قَتِيلَ الْخَطَإِ قَتِيلَ السَّوْطِ وَالْعَصَا فِيهِ مِائَةٌ مِنَ الإِبِلِ مُغَلَّظَةٌ أَرْبَعُونَ مِنْهَا فِي بُطُونِهَا أَوْلاَدُهَا ‏"‏ ‏.‏

It was narrated from 'Uqbah bin 'Aws, that the Mssenger of Allah said:"Indeed the accidental killing, the killing with a whip or stick, for it (the Diyah) is one hundred camels - a severe penalty - of which forty should be (she-camels) with their young in their wombs

Reference

Sunan an-Nasa'i 4795

In-book

Book 45, Hadith 90