two are the things which I remember Messenger of Allah ﷺ having said: "Verily Allah has enjoined excellence to everything; so when you kill, kill in a good way and when you slaughter, slaughter in a good way. So every one of you should sharpen his knife, and let the slaughtered animal die comfortably." (Using translation from Muslim 1955a)
"إِن الله تعالى كَتَبَ الإِحسانَ على كل شَيء، فإِذا قتلتُم فَأحسِنوا القِتْلَةَ، وَإذَا ذبحتم فَأَحْسِنوا الذِّبحةَ، ولْيُحِدَّ أَحدُكم شَفْرتَهُ، وَلْيُرِحْ ذبيحته".