Reversal and juxtaposition of the first and third chapters.

"the word of the LORD came to..." used over 100x in the OT.
Both times here:
GOD: "Get up and go..."
JONAH: "Got up and went..."
But the 1st time, Jonah went away.
THIS TIME, Jonah obeys and goes where God told him to go.

Will be overturned. The verb hāpak, ‘overturn’, is used elsewhere to describe the destruction of Sodom and Gomorrah (Gen. 19:25; Lam. 4:6; Amos 4:11). The basic idea underlying the verb is ‘to turn’. On occasions it means ‘to overturn’ (2 Kgs 21:13, ‘to overturn a plate’). However, it can also mean ‘to turn around’, ‘transform’ (1 Kgs 22:34, ‘to turn around a chariot’; Jer. 13:23, ‘to transform one’s appearance’). With these different connotations the use of the word here is hardly accidental. Although Nineveh was not overturned, it did experience a turn around."

Donald J. Wiseman, T. Desmond Alexander, and Bruce K. Waltke, Obadiah, Jonah and Micah: An Introduction and Commentary, vol. 26 of Tyndale Old Testament Commentaries (Downers Grove, IL: InterVarsity Press, 1988), 133–134.

THIS IS ABOUT GOD'S GRACE.
Because GRACE is meaningless if there is no consequence otherwise.

The Ninevites (much like the pagan sailors before them) believed God (or believed in God) and repented.

This is what God expects of Jonah, to believe God and obey.
This is what God expects of Israel, but rarely gets from them.
This is what God expects...

Some word play:
there's a lot of "cry out" and "proclaim".
There's a lot of "repent/turn/relent/change"

Here, the king:
Arises.
puts OFF clothes
puts ON sackcloth
Sits down.

Chiastic journey.
Transformation.
The message goes from the lowest people and animals,
to the highest (king) person,
who makes himself low.

THIS IS THE GOSPEL: ALL ARE SAVED BY FAITH IN CHRIST.
EVERY KNEE WILL BOW. EVERY TONGUE CONFESS: "JESUS IS LORD"

"Maybe he will relent..."
AND HE DOES!

Now. God does not "repent" like we think of it... he's not "sorry" that he was going to, or did anything wrong.
God changes course. He doesn't destroy Nineveh (at that time).
That's what repentance is (biblically).
He turned from where he was / what he was going to do.

THIS IS ABOUT YHWH.
THIS IS ABOUT OBEDIENCE.
THIS IS ABOUT GRACE.
THIS IS ABOUT REPENTANCE.

Targum Jonathan (a translation of the Prophets into Aramaic, for use in the synagogue) addresses this question in its introduction to Nahum: “In former times, Jonah son of Amittai, the prophet from Gath Hepher, prophesied against her, and she repented from her sins, but then, when she sinned again, Nahum of the house of Qoshi prophesied against her again, as is written in this book” (Nah 1:1). The implicit message of the Twelve to its readers is that God’s forgiveness cannot be taken for granted. Although the Lord is “a gracious God and merciful, slow to anger, and abounding in steadfast love, and ready to relent from punishing” (Jonah 4:2; compare Exod 34:6–7 and Nah 1:3), it is disastrous to presume upon the Lord’s grace.

Steven Tuell, “Nahum, Book of,” in The Lexham Bible Dictionary, ed. John D. Barry et al. (Bellingham, WA: Lexham Press, 2016).

WILL YOU OBEY GOD?
Will you share the good news, that in Christ there is life?
THERE IS PEACE WITH GOD, FOR EVERYONE WHO BELIEVES, THROUGH CHRIST JESUS.

EXAMINE YOUR HEART.
TURN TO GOD.
REPENT.

If you have done so, then know that the path God is placing you on includes sharing this good news with others.

AND KNOW THAT FOR THEM AND FOR YOU, THERE IS GRACE IN CHRIST.