Ps 51:16-17, Isa 1:11-18, Hos 6:6-7, Acts 5:30-32, Jn 17:3

In the Old Testament, God, through Samuel, commanded King Saul to kill all the Amalekites. But King Saul spared Amalek's good sheep and cattle to give to God. Then Samuel told King Saul that God wanted to obey God's word rather than sacrifice. (1 Samuel 15:22)

1 Samuel 15:22 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.

What God wants through the sacrifice is that the people of Israel truly know God. (Psalm 51:16-17; Hos 6:6)

Psalm 51:16 For thou desirest not sacrifice; else would I give it: thou delightest not in burnt offering. 17 The sacrifices of God are a broken spirit: a broken and a contrite heart, O God, thou wilt not despise.

Hos 6:6 For I desired mercy, and not sacrifice; and the knowledge of God more than burnt offerings.

In the Old Testament, the Israelites offered sacrifices to God, but they refused to truly know God. (Isa 1:11-18)

Isa 1:11 To what purpose is the multitude of your sacrifices unto me? saith the Lord: I am full of the burnt offerings of rams, and the fat of fed beasts; and I delight not in the blood of bullocks, or of lambs, or of he goats. 12 When ye come to appear before me, who hath required this at your hand, to tread my courts? 13 Bring no more vain oblations; incense is an abomination unto me; the new moons and sabbaths, the calling of assemblies, I cannot away with; it is iniquity, even the solemn meeting. 14 Your new moons and your appointed feasts my soul hateth: they are a trouble unto me; I am weary to bear them. 15 And when ye spread forth your hands, I will hide mine eyes from you: yea, when ye make many prayers, I will not hear: your hands are full of blood. 16 Wash you, make you clean; put away the evil of your doings from before mine eyes; cease to do evil; 17 Learn to do well; seek judgment, relieve the oppressed, judge the fatherless, plead for the widow. 18 Come now, and let us reason together, saith the Lord: though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool.

To believe in Jesus as the Christ is to know God and obey God's will. So God pours out the Holy Spirit on those who believe that Jesus is the Christ. (Acts 5:31-32, John 17:3)

Acts 5:30 The God of our fathers raised up Jesus, whom ye slew and hanged on a tree. 31 Him hath God exalted with his right hand to be a Prince and a Saviour, for to give repentance to Israel, and forgiveness of sins. 32 And we are his witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey him.

John 17:3 And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent.