An-Nawawi Hadith - 17

إِنَّ اللهَ كَتَبَ الإِحْسَانَ عَلَى كُلِّ شَيْءٍ: فَإِذَا قَتَلْتُمْ فَأَحْسِنُوا الْقِتْلَةَ، وَإِذَا ذَبَحْتُمْ فَأَحْسِنُوا الذِّبْحَةَ، وَلْيُحِدْ أَحَدُكُمْ شَفْرَتَهُ، وَلْيُرِحْ ذَبِيحَتَهُ رَوَاهُ وَمُسْلِمٌ

Abu Ya'la Shaddad ibn Aus, radiyallahu 'anhu, reported that the Messenger of Allah, sallallahu 'alayhi wasallam, said: "Verily, Allah has enjoined excellence (ihsan) with regard to everything. So, when you kill, kill in a good way; when you slaughter, slaughter in a good way; so everyone of you should sharpen his knife, and let the slaughtered animal die comfortably." [Muslim]