Sahih Muslim Book 21, Hadith Number 4810.

Chapter : Good attitude even in slaughter and killing and sharpening of large knife.

Shaddid b. Aus said: Two are the things which I remember Allah’s Messenger (may peace be upon him) having said: Verily Allah has enjoined goodness to everything; so when you kill, kill in a good way and when you slaughter, slaughter in a good way. So every one of you should sharpen his knife, and let the slaughtered animal die comfortably.