Paul anticipates a human reaction to God's choice of Jacob over Esau. Paul anticipates men judging God and accusing God of unjust. And yet we know from studying God's attributes (see discussion of God's attribute of Justice), that He is always fair. He is never unjust in His essence. So here we see where human logic comes to a "logical" but wrong conclusion.

THERE IS NO INJUSTICE (unrighteousness) WITH GOD IS THERE: me adikia para to theo: (2:5; 3:5,6; Genesis 18:25; Deuteronomy 32:4; 2 Chronicles 19:7; Job 8:3; 34:10-12,18,19; Job 35:2; Psalms 92:15; 145:17; Jeremiah 12:1; Revelation 15:3,4; 16:7)

Injustice (93) (adikia from a = negates what follows + dike = right) describes the condition of not being right. Adikia describes unrighteousness of heart and life resulting in wrongdoing. It can describe a  deed violating law and justice.

He is going to say that it is not a matter of injustice but a matter of mercy. God sovereignly (See attribute  Sovereign) has mercy (see attribute Mercy) on who He will although all deserve His wrath (see attribute  Wrath).

MAY IT NEVER BE: me genoito (3SAMO): Away with the thought. Perish the thought. By no means! Certainly not!

Phillips renders it

The connection and the argument are obvious:

 “It is not unjust for God to exercise his sovereignty in the distribution of his mercies, for he expressly claims the right.”

HE SAYS TO MOSES I WILL HAVE MERCY ON WHOM I HAVE MERCY: to Mousei gar legei (1SPAI): eleeso (1SFAI) on an eleo (1SPAS): (16,18,19; Exodus 33:19; 34:6,7; Isaiah 27:11; Micah 7:18)

Paul quotes the Septuagint (LXX) of (Exodus 33:19)

Paul has already shown us that all mankind is under sin (Romans 3:9-10,19,23 6:23) and justly deserves God's righteous wrath (see note on Romans 1:18). But God who is rich is mercy (see His attribute Mercy)  looks down and has mercy on some and compassion on some. He has mercy and compassion on whomever He chooses. This should cause us to fall on our face and cry out

"Have mercy on me when I justly deserve hell."

What awesome truth this is.

Mercy (1653) (eleeo, from eleos = mercy) means to show mercy. It means to extend help for the consequence of sin. It means to have compassion or mercy on a person in unhappy circumstances.

Mercy implies that there is absolutely nothing within us that caused God to bestow His mercy upon us. It is simply according to His good pleasure. There was nothing in us to commend us to God. We could do nothing to help ourselves (Ro 5:6, 8, 10). Mercy also implies that the one bestowing the mercy has the means to meet the need. Here God meets the need of those He chooses.

AND I WILL HAVE COMPASSION ON WHOM I HAVE COMPASSION: kai oiktireso (1SFAI) on an oiktiro (1SFAI):

Compassion (3627) (oikteiro) means to exercise pity or to have compassion on.

Mercy (eleeo) expresses the heart motivation and compassion  (oikteiro)  the manifestation of that feeling.

The reference in Ex 33 deals with Israel’s idolatry while Moses was on the mount receiving the Law (Ex 32:4ff). The whole nation deserved to be destroyed, yet God killed only 3,000 people (Ex 32:27-28) not because they were more wicked or less godly, but purely because of His grace and mercy.

In other words, His sparing the people and continuing to guide and protect them was purely reflective of His mercy and grace. He had the absolute right to condemn or to save as He divinely saw fit. God’s sovereignty and His grace not only are compatible but are inseparable.

Spurgeon comments...

 It is equally true that he wills to have mercy, and has already had mercy on every soul that repents of sin and puts its trust in Jesus.—13.309

If there is one doctrine in the world which reveals the enmity of the human heart more than an-other, it is the doctrine of God's sovereignty. When men hear the Lord's voice saying, "I will have mercy on whom I will have mercy," they gnash their teeth and call the preacher an An­tinomian, a High Calvinist, or some other hard name. They do not love God except they can make him a little God. They cannot bear for him to be su­preme. They would gladly take his will away from him and set up their own will as the first cause

Spurgeon writes in his devotional that...

This means that God’s mercy and compassion cannot be subject to any cause outside his free grace. God had mercy on the Israelites (not destroying them for their idolatry), not because they deserved it, but simply because he chose to be merciful.

This is a picture of human thinking and striving as seen in John's description of those who became children of God by faith and...

who were born not of blood, nor of the will of the flesh, nor of the will of man, but of God. (John 1:12,13)

Did you come to God because you wanted to come to God? You would not have even wanted to unless God had placed that desire in your heart to even want Him. So it is not because you actively willed & purposed or resolved to come to God.

BUT ON GOD WHO HAS MERCY: alla tou eleontos (PAPMSG) theou: (11; Genesis 27:1-4,9-14; Psalms 110:3; Isaiah 65:1; Matthew 11:25,26; Luke 10:21; John 1:12,13; 3:8; 1 Corinthians 1:26-31; Ephesians 2:4,5; Philippians 2:13; 2 Thessalonians 2:13,14; Titus 3:3-5; James 1:18; 1 Peter 2:9,10)

It is not man’s choice or pursuit but God who initiates mercy for the sinner. Salvation is never initiated by human choice or merited by zealous human effort. It always begins in God’s sovereign, gracious, and eternal will. Those who receive God’s mercy receive it solely by His grace.

Ishmael desired ("the man who wills") the blessing but failed to receive it. Esau ran ("the man who runs") for the blessing, as it were, but also failed to receive it (Ge27). Esau received a blessing from his father but not the blessing he sought with tears, because he was ungodly and sought the blessing without repentance or faith (Heb12:16-17).

Paul writes of God's mercy on those dead in their trespasses and sins...

But God, being rich in mercy, because of His great love with which He loved us, even when we were dead in our transgressions, made us alive together with Christ (by grace you have been saved), (sermon on Ephesians 2:4-5)

And again in Titus God showed mercy on those who were foolish , disobedient, deceived, enslaved to various lusts and pleasures, spending their life in malice and envy, hateful, hating one another, Paul recording that...

 when the kindness of God our Savior and His love for mankind appeared, He saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit, (see notes on Titus 3:4 Titus 3:5)

Finally Peter says

Blessed be the God and Father of our Lord Jesus Christ, who according to His great mercy has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, (see notes on 1 Peter 1:3)

G Campbell Morgan writes that Paul...

Being an absolute monarch, Pharaoh assumed that, certainly within his own realm, everything he said and did was by his own free choice to serve his own human purposes. But the Lord made clear through Moses that Pharaoh was divinely raised up to serve a divine purpose, a purpose of which the king was not even aware.

FOR THIS VERY PURPOSE I RAISED YOU UP: hoti eis auto touto exegeira (1SAAI) se opos:

Paul quotes the Septuagint (LXX) of (Exodus 9:16)

Paul does say "for this very purpose I created you". Out of a mass of unregenerate mankind God raises up a man who had suppressed the truth, who refused to give God thanks and honor, exchanging His truth for the lie and who was therefore without excuse (see notes on Romans 1:20-21).

God This is who God called forth (almost as one would do in a play) on to the stage of world history (His story) saying in essence "I will use you to demonstrate my power." It is not as if Pharaoh had said I want to believe in You and be saved. In fact when Pharaoh is faced with the clear demonstration of God's power and refuses to bow down, instead becoming becoming hardened. And Pharaoh is used for God's purposes to deliver many from bondage.

Raised up (1825) (exegeiro from ek = out + egeíro = to raise) carries the idea of bringing forward or lifting up and was used of the rise of historical figures to positions of prominence. The word is used several times in the Septuagint (LXX).

Speaking through the prophet Nathan, the Lord told David that, because of his murder of Uriah and taking his wife, Bathsheba, for himself,

“I will raise up evil against you from your own household” (2 Sa 12:11).

One of Job’s “comforters” rightly said of God that

“He sets on high those who are lowly, and those who mourn are lifted to safety” (Job 5:11)

In much the same way that He raised up Pharaoh, the Lord also raised up “the Chaldeans” to do His will, Habakkuk recording God's declaration...

"behold, I am raising up the Chaldeans, that fierce and impetuous people who march throughout the earth To seize dwelling places which are not theirs." (Hab. 1:6)

Zechariah records that one day will

“raise up a shepherd [Antichrist] in the land who will not care for the perishing, seek the scattered, heal the broken, or sustain the one standing, but will devour the flesh of the fat sheep and tear off their hoofs” (Zec11:16).

All of these events (and others too numerous to mention) underline the truth that God is sovereign over history. (See attribute  Sovereign)

TO DEMONSTRATE MY POWER IN YOU: endeixomai (1SAMS) en soi ten dunamin mou:

Demonstrate (1731) (endeiknumi from en = in, to + deíknumi = make known the character or significance of something by visual, auditory, gestural, or linguistic means) means to show forth, demonstrate or prove, whether by arguments or acts.

AND THAT MY NAME MIGHT BE PROCLAIMED THROUGHOUT THE WHOLE EARTH: kai opos diaggele (3SAPS) to onoma mou en pase te ge: (Exodus 10:1,2; 14:17,18; 15:14,15; 18:10,11; Joshua 2:9,10; 9:9; 1 Samuel 4:8) (John 17:26)

Proclaimed (1229) (diaggello from diá = through + aggéllo = to tell, declare) means to herald thoroughly, to declare fully or far and wide and so to declare plainly, fully and exactly.

The psalmist Asaph appeals to God not to remain silent or still as His enemies exalt themselves pleading with Him to...

Let them be ashamed and dismayed forever; and let them be humiliated and perish, that they may know that Thou Alone, Whose Name is the LORD, art the Most High over all the earth. (Psalms 83:17,18)

In Isaiah King Hezekiah appeals to the Lord (for Israel's deliverance) that His name might be proclaimed...

"And now, O LORD our God, deliver us from his hand that all the kingdoms of the earth may know that Thou alone, LORD, art God." (Isaiah 37:20)

Solomon writes that...