al-Zuhri ابن شهاب الزهري‎, محمد بن مسلم · The Book of ad-Dahaya (Sacrifices)

"I heard two things from the Messenger of Allah He said 'Allah, the Mighty and Sublime, ahs 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 spear suffering to the animal he slaughter."" (Sahih )

"Two things that I memorized form the Messenger of Allah; 'Allah, the Mighty and Sublime, 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 slaughter,"" (Sahih )

"The Messenger of Allah sacrificed two horned, Amlah rams, saying: 'Allah Akbar and pronouncing the Name of Allah. I saw him slaughtering them with his own hand, and placing his foot on their sides." I said: You heard it from Him? He said: Yes. (Sahih )