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 translation
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]