Sunan an-Nasa'i 4796
سنن النسائي#4796SahihIt was narrated from Ya'qub bin Aws, from a man among the Companions of the Prophet that:when the Messenger of Allah entered Makkah on the Day of the Conquest, he said: "Indeed, every accidental killing on purpose, or resembling on purpose - killing with a whip or stick, for it are forty (she-camels) which their young in their wombs
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih Lighairihi
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 45:91