Abu Ya'la Shaddad bin 'Aus (May Allah be pleased with him) reported:
Messenger of Allah (ﷺ) said, "Verily Allah has prescribed Ihsan (kindness) for everything. So when you kill, you must make the killing in the best manner; when you slaughter, make your slaughter in the best manner. Let one of you sharpen his knife and give ease to his animal (in order to reduce his pain)."[Muslim].
Arabic/English book reference: Book 1, Hadith 640