Explanation

The Prophet (may Allah's peace and blessings be upon him) informs that Allah Almighty prescribed ihsān (kindness/excellence) upon us in everything. Ihsān: It is constantly being heedful of Allah in worshipping Him, doing good, and abstaining from harming other created beings. An aspect of this is ihsān in killing and slaughtering. Ihsān in killing, for legal retribution, is to choose the easiest method which causes the least suffering to the one being killed and the quickest in taking his life. Ihsān in slaughtering animals is to show kindness toward the animal by sharpening the blade and not sharpening it while the animal is looking on, and not slaughtering an animal while another animal is looking.