Concept:God demands complete obedience to His direct commands, not partial obedience driven by human judgment.
Explanation:God sent the prophet Samuel to command Saul to attack the Amalekites and completely destroy all their people and possessions.
Saul defeated the Amalekites in battle, but he spared their king, Agag, and kept the best of the sheep and cattle.
When Samuel confronted him, Saul claimed the animals were kept for sacrifice to the Lord.
Samuel responded that obedience is better than sacrifice, and that rebellion is like the sin of divination.
This instruction concerned the Amalekites, not the Philistines, so options B and C are incorrect.
Trying to kill David was a later act of jealousy, not the specific disobedience referred to here, so option A is incorrect.
Because Saul did not fully carry out God's command, the Lord rejected him as king over Israel.
Answer:King Saul disobeyed God by not destroying the Amalekites completely, so the correct option is D.