Compiled by Imam Yahya ibn Sharaf al-Nawawi
عَنْ أَبِي يَعْلَى شَدَّادِ بْنِ أَوْسٍ رَضِيَ اللهُ عَنْهُ عَنْ رَسُولِ اللَّهِ صلى الله عليه و سلم قَالَ: "إنَّ اللَّهَ كَتَبَ الْإِحْسَانَ عَلَى كُلِّ شَيْءٍ، فَإِذَا قَتَلْتُمْ فَأَحْسِنُوا الْقِتْلَةَ، وَإِذَا ذَبَحْتُمْ فَأَحْسِنُوا الذِّبْحَةَ، وَلْيُحِدَّ أَحَدُكُمْ شَفْرَتَهُ، وَلْيُرِحْ ذَبِيحَتَهُ". [رَوَاهُ مُسْلِمٌ].
Verily Allah has prescribed ihsan (proficiency, perfection) in all things. So if you kill then kill well; and if you slaughter, then slaughter well. Let each one of you sharpen his blade and let him spare suffering to the animal he slaughters.” [Muslim]