أَخْبَرَنِي يَحْيَى بْنُ حَبِيبِ بْنِ عَرَبِيٍّ، قَالَ أَنْبَأَنَا حَمَّادٌ، عَنْ خَالِدٍ، - يَعْنِي الْحَذَّاءَ - عَنِ الْقَاسِمِ بْنِ رَبِيعَةَ، عَنْ عُقْبَةَ بْنِ أَوْسٍ، عَنْ عَبْدِ اللَّهِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ أَلاَ وَإِنَّ قَتِيلَ الْخَطَإِ شِبْهِ الْعَمْدِ مَا كَانَ بِالسَّوْطِ وَالْعَصَا مِائَةٌ مِنَ الإِبِلِ أَرْبَعُونَ فِي بُطُونِهَا أَوْلاَدُهَا ‏"‏ ‏.‏

It was narrated from Ya'qub bin Aws that

a man from among the Companions of the Prophet told him, that when the Messenger of Allah came to Makkah, in the Year of the Conquest, he said: "Indeed, accidental killing on purpose, is killing with a whip or stick, for which forty (she-camels) with their young in their wombs."