1 Samuel 15:19
Wherefore then didst thou not obey the voice of the LORD, but didst fly upon the spoil, and didst evil in the sight of the LORD? Wherefore then didst thou not obey the voice of the LORD, but didst fly upon the spoil, and didst evil in the sight of the LORD?
The question rebukes Saul for turning aside from the command to execute justice upon Amalek by destroying everything, and instead flying upon and seizing the spoil and doing evil in the sight of the Lord. The disobedience lay in not obeying the voice of the Lord and not carrying the command fully through, choosing what he wanted over the word given through Samuel. His claim to have obeyed only exposed the contradiction between professed obedience and conduct against God's word.
What he kept were Agag and the best of the animals, the livestock, sheep and oxen, sparing the king and the best rather than destroying everything as commanded. In doing so he chose his own course and reasoning instead of following God, acting for what he wanted, for renown and material gain. Pride went with that disregard of the command, and with failure to credit God for Israel's victory.
The taking of the spoil was disobedience and self-exalting reasoning, evil in the sight of the Lord. His claim to have obeyed was false, and the kept sheep and oxen laid bare the falsehood, showing loyalty professed with the lips contradicted by a life that disregarded His voice. Self-justification rather than repentance was his answer when the facts confronted him.
He tried to excuse himself by laying blame on the people and by pleading a religious purpose, that the animals were kept for sacrifice as an offering to God. That purpose did not turn the act into obedience, and the religious plea did not make the disobedience acceptable. To use God's cause to cover ambition, pride, display, or injustice only makes the sin more grievous.
Through the prophet he was confronted and held accountable, his self-justification exposed and an account of his rebellion demanded. When rebuked he justified himself instead of admitting disobedience and repenting, denying wrongdoing until the facts were undeniable, making no confession. He counted himself misused and ill-treated, a pattern repeated in others who follow the same course.
The verse teaches that obedience to God's word is better than sacrifice, and that rebellion and stubbornness are grave sins. Knowingly to violate God's law for material gain brings judgment, and Saul's rejection of God's word brought his own rejection as king. God bears long with men, but persistent disregard of sufficient light brings destruction, and without Christ's transforming grace and daily humility before God rebellion persists and leads on to further wrong.