Nawawi 40 · #17
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]
English
On the authority of Abu Ya’la Shaddad bin Aws (may Allah be pleased with him), that the Messenger of Allah (peace and blessings of Allah be upon him) said: 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]