Saul destroyed an enemy, but failed to utterly destroy them, as God had commanded him. Instead, he saved the choice animals and offered them as a sacrifice to God. "And Samuel said, Hath the Lord as great delight in burnt offerings and sacrifices, as in obeying the voice of the Lord? Behold, to obey is better than sacrifice, and to hearken than the fat of rams." (1 Sam 15:22) The law of sacrifice is NOT selecting what you will sacrifice to the Lord. It is not imaging up what you think would be good for you to do and then doing it. It is asking God what he wants you to do, and then doing it. Sometimes it is easy for us to get carried away imaging what would be pleasing to God. We end up stretching ourselves in vain, while ignoring the real soul-burning offering that God has asked of us. Most times, this harrowing experience is very personal and possibly even invisible to those around you (though sometimes it is public). God is not pleased by the quantity of what we give.