I believe if you read what the Bible says your question is answered by God Himself;
Genesis 17.8 The Amalekites came and attacked the Israelites at Rephidim.
Genesis 17.14 Then the LORD said to Moses, “Write this on a scroll as something to be remembered and make sure that Joshua hears it, because I will completely blot out the memory of Amalek from under heaven.”
Deuteronomy 25:17 Remember what the Amalekites did to you along the way when you came out of Egypt.
Judges 6:3Whenever the Israelites planted their crops, the Midianites, Amalekites and other eastern peoples invaded the country.
Judges 7:12 The Midianites, the Amalekites and all the other eastern peoples had settled in the valley, thick as locusts. Their camels could no more be counted than the sand on the seashore.
1 Samuel 15:2 This is what the LORD Almighty says: ‘I will punish the Amalekites for what they did to Israel when they waylaid them as they came up from Egypt.
1 Samuel 15:3 Now go, attack the Amalekites and totally destroy [a] everything that belongs to them. Do not spare them; put to death men and women, children and infants, cattle and sheep, camels and donkeys.’ “
1 Samuel 15:8 He took Agag king of the Amalekites alive, and all his people he totally destroyed with the sword.
1 Samuel 15:15 Saul answered, “The soldiers brought them from the Amalekites; they spared the best of the sheep and cattle to sacrifice to the LORD your God, but we totally destroyed the rest.”
16 “Stop!” Samuel said to Saul. “Let me tell you what the LORD said to me last night.”
“Tell me,” Saul replied.

17 Samuel said, “Although you were once small in your own eyes, did you not become the head of the tribes of Israel? The LORD anointed you king over Israel. 18 And he sent you on a mission, saying, ‘Go and completely destroy those wicked people, the Amalekites; make war on them until you have wiped them out.’ 19 Why did you not obey the LORD ? Why did you pounce on the plunder and do evil in the eyes of the LORD ?”

20 “But I did obey the LORD,” Saul said. “I went on the mission the LORD assigned me. I completely destroyed the Amalekites and brought back Agag their king. 21 The soldiers took sheep and cattle from the plunder, the best of what was devoted to God, in order to sacrifice them to the LORD your God at Gilgal.”

22 But Samuel replied:
“Does the LORD delight in burnt offerings and sacrifices
as much as in obeying the voice of the LORD ?
To obey is better than sacrifice,
and to heed is better than the fat of rams.

23 For rebellion is like the sin of divination,
and arrogance like the evil of idolatry.
Because you have rejected the word of the LORD,
he has rejected you as king.”

This is a stern warning!

GOD MAKES PROMISES IN HIS WORD AND YOU BETTER BELIEVE HE WILL KEEP THEM
also note how it is better to obey than to offer sacrifices.
We as Christians today better take bake the truth we have in Gods promises and know that God will keep His promises and His word stands true through the ages.