What does God mean when He says, “I will have mercy on whom I will have mercy” (Exodus 33:19)?
Again, we quote from the website gotquestions.org.
After the Israelites sinned against God by worshipping the golden calf, the Lord was ready to send them to the Promised Land on their own without Him (Exodus 33:3). But Moses interceded for the people (Exodus 33:12–17). During his private meeting with Yahweh, Moses asked God for assurances, one being, “Please, let me see Your glory” (Exodus 33:18, CSB). God answered, saying, “I will cause all my goodness to pass in front of you, and I will proclaim my name, the LORD, in your presence. I will have mercy on whom I will have mercy, and I will have compassion on whom I will have compassion” (Exodus 33:19).
Ever the faithful mediator, Moses asked God not to destroy the Israelites but to stay with His people to lead them to the Promised Land. God agreed to live among them and come down to them in glory in His tabernacle. The Lord promised Moses, “I will indeed do what you have asked, for I look favorably on you, and I know you by name” (Exodus 33:17, NLT).
Moses, who had already received glimpses of God’s glory at the burning bush (Exodus 3:1–22), on the mountaintop (Exodus 24:15–18), and at the tent of meeting (Exodus 33:12–23), asked to see more. He wanted a greater revelation of God’s glory. The Lord’s answer was part yes and part no. God was willing to show all of His divine goodness to Moses. He was pleased to call out His sacred name, Yahweh*,before Moses. And He was ready to reveal His sovereign mercy and compassion to Moses. God would show as much of Himself as Moses was able to bear, but there were limits. If Moses were to see a complete revelation of God’s glory, it would be so overwhelming that it would destroy him (Exodus 33:20).* Yahweh or, more correctly, YHWH, MEANS I AM WHO I AM. It is the Name too sacred to be spoken
By not fully answering Moses’ request, God was in actuality exhibiting mercy and compassion toward Moses. When He said to Moses, “I will have mercy on whom I will have mercy” in Exodus 33:19, the Lord meant that He shows mercy freely to anyone He chooses. The New Living Translation renders the meaning of the verse more explicitly: “I will show mercy to anyone I choose, and I will show compassion to anyone I choose.”
Demonstrating mercy is one way God reveals His glory. The word mercy in Exodus 33:19 means “kindness, compassion, and forgiveness.” When God said, “I will have mercy on whom I will have mercy,” He meant that He would show kindness, compassion, and forgiveness to anyone He chooses.
God’s mercy—His wondrous compassion—leads Him to forgive sinners and withhold the punishment that is justly deserved. After the Lord graciously led the Israelites out of slavery in Egypt, through the Red Sea, and toward the Promised Land, they responded by revolting against God. Yet, because of the favor obtained through their mediator, Moses, God was pleased to lavish His mercy on them.
Exodus 33:19 is quoted in the New Testament by the apostle Paul in reference to the sovereignty of God: “For God said to Moses, ‘I will show mercy to anyone I choose, and I will show compassion to anyone I choose’” (Romans 9:15, NLT). Paul meant that God’s freedom is absolute. It is essential to understand that, before God, humans have no rights or privileges. We have no claim of our own to God’s mercy. That is why the concept and outworking of mercy are so crucial for sinners.
“I will have mercy on whom I will have mercy” means God’s freedom to demonstrate mercy is not limited by anything but His own divine choice. God does not show mercy because humans deserve it. The Lord’s favor cannot be earned by status, social class, or works of righteousness—otherwise, it would not be mercy.
The Lord said He had mercy on Israel because He was pleased with their mediator, the prophet Moses: “I will do the very thing you have asked, because I am pleased with you” (Exodus 33:17). God chose to extend the grace, favor, and love that He had for Moses to the children of Israel. The people were spared, by divine choice, through the merits of Moses, their mediator. This act was a foreshadowing of our basis of salvation in Christ.
Humans cannot be saved based on their own efforts (Ephesians 2:8–9). The Bible says we are too sinful to merit salvation (Isaiah 64:6; Romans 3:10, 23; Psalm 143:2). Our salvation hinges on the pleasure God takes in our Mediator—the person of Jesus Christ, God’s Son and our Savior (Hebrews 9:15; Galatians 2:16). Since God is pleased with Jesus (Matthew 3:17; 17:5), He is pleased with anyone who trusts in Him for salvation. Jesus is our Mediator, accomplishing for us what Moses did for Israel, only in perfection. https://www.gotquestions.org/I-will-have-mercy.html