Sunan an-Nasa'i 4405
سنن النسائي#4405SahihIt was narrated that Shaddad bin Aws said:"There are two things that I memorized from the Messenger of Allah, who said: 'Allah has decreed proficiency in all things, so when you kill, kill well, and when you slaughter, slaughter well. Let one of you sharpen his blade and spare suffering to the animal he slaughters.'" (Sahih)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 43:45