1 Samuel 15:2-3
15:2 This is what the LORD Almighty [literally “Lord of hosts” or “Lord of armies”] says: ‘I will punish the Amalekites [loosely allied group of nomads who occupied territory south of Judah; had a long history of hostility against the Jews and God’s purposes] for what they did to Israel when they waylaid [by means of barbaric guerrilla warfare (cf. Ex. 17:8; Deut. 25:17-19)] them as they came up from Egypt [cf. Deut. 25:17-19].

15:3 Now go, attack the Amalekites and totally destroy everything [Heb. cherem: term used to describe something entirely given over to God, devoted to Him; without reservation or exception] that belongs to them. Do not spare them [Israelites were to fight as God’s agents of judgment, not for their own profit; cf. Deut. 20:18 re: reason for total destruction of enemy; would also serve as an example to those who would do evil against God’s people]; put to death men and women, children and infants, cattle and sheep, camels and donkeys.’”

15:4-7 Saul led army of 210,000 to victory over Amalekites.

15:8-9 Saul spared Agag king of the Amalekites and the best of the sheep and cattle.

15:10-12 The Lord grieved that He had made Saul king.

1 Samuel 15:13-15
15:13 When Samuel reached him, Saul said [with enthusiasm], “The LORD bless you! I have carried out the LORD’S instructions.”

15:14 But Samuel said [exposed Saul’s lie], “What then [in essence: “If you have obeyed God’s instructions, then explain what I am hearing. How can slaughtered livestock make sounds?”] is this bleating of sheep in my ears? What is this lowing of cattle that I hear [Samuel heard the sounds of Saul’s disobedience]?”

15:15 Saul answered [rationalization: twisting facts and misstating motives], “The soldiers [Saul blamed others and excused himself (a common response of those caught in disobedience); soldiers could not have acted without Saul’s consent] brought them from the Amalekites; they spared the best of the sheep and cattle to [attempt to excuse and to justify actions] sacrifice [Saul did nor grasp contradiction between disobeying God and then offering sacrifices with these animals; “a gross deception, an attempt to conceal the selfishness of the original motive under the cloak of religious zeal and gratitude” (Jameison-Faussett-Brown Commentary)] to the LORD your God, but we totally destroyed the rest.”

15:16-18 Samuel told Saul what God had revealed to him the previous night.

1 Samuel 15:19-23
15:19 [Samuel put Saul on the spot] Why did you not obey [or “hear” – hearing to the Hebrews implied obedience] the LORD? Why did you pounce on the plunder [Saul cared more for “plunder” than for the Lord] and do evil [to disobey is to do evil] in the eyes of the LORD [everything we do and fail to do is in God’s sight]?”

15:20 “But I did obey the LORD,” Saul said. “I went on the mission the LORD assigned me. I completely [means without reservation or exception] destroyed the Amalekites and [Saul revealed his disobedience and condemned himself] brought back Agag their king [God’s command was to “totally destroy everything” (v. 3)].

15:21 The soldiers took [God never instructed them to take anything] sheep and cattle from the plunder, the best of what was devoted to God, in order to [Saul tried to cast their actions in a spiritual light] sacrifice [neither God nor Samuel had instructed Saul to do this] them to the LORD your God at Gilgal.”

15:22 But Samuel replied [a lesson in spiritual priorities]: “Does the LORD delight in burnt offerings and sacrifices as much as in obeying the voice of the LORD [obvious answer is “no” – God delights in our obedience]? To obey [the central tenet of Israel’s law (cf. Ex. 19:5; Deut. 6:24-25; 30:14)] is better than sacrifice, and to heed is better than the fat [the choicest part of the sacrifice] of rams.

15:23 For rebellion [disobedience to God’s command] is like [is equally sinful to] the sin of divination [the use of magical means to seek guidance or know the future], and arrogance [Saul made himself the final authority on obedience] like the evil of idolatry [the worship of false gods]. Because you have rejected [cf. Prov. 13:13; 28:9] the word of the LORD, he has rejected you as king [position of responsibility; Saul not rejected as a person].”

15:24-31 Samuel told Saul that the Lord was going to take the kingdom away from him.

15:32-33 Samuel killed Agag king of the Amalekites.

15:34-35 Samuel and Saul parted company, never to see each other again.