Albert Barnes Commentary Jonah 4:5

"Then Jonah went out of the city, and sat on the east side of the city, and there made him a booth, and sat under it in the shade, till he might see what would become of the city." — Jonah 4:5 (ASV)

So Jonah went out of the city - The form of the words implies (as in the English Version) that this took place after Jonah was convinced that God would spare Nineveh. Since there is no indication that he knew it by revelation, it was probably after the 40 days.

“The days now being past, after which it was time for the foretold events to be accomplished, and His anger still taking no effect, Jonah understood that God had pity on Nineveh. Still, he does not give up all hope. He thinks that a respite from the evil has been granted them for their willingness to repent, but that some effect of His displeasure would come, since the pains of their repentance had not equaled their offenses. So, thinking this to himself, apparently, he departs from the city and waits to see what will become of them.”

“He expected,” apparently, “that it would either fall by an earthquake or be burned with fire, like Sodom.”

“Jonah, in that he built himself a tabernacle and sat opposite Nineveh, awaiting what should happen to it, represented a different, prefiguring character.

For he prefigured the carnal people of Israel. For these too were sad at the salvation of the Ninevites, that is, the redemption and deliverance of the Gentiles. Therefore Christ came to call, not the righteous but sinners to repentance.

But the overshadowing gourd over his head symbolized the promises of the Old Testament, or those offices in which, as the apostle says, there was a shadow of good things to come, protecting them in the land of promise from temporal evils, all of which are now emptied and faded.

And now that people, having lost the temple at Jerusalem, the priesthood, and the sacrifice (all of which was a shadow of that which was to come) in its captive dispersion, is scorched by a vehement heat of tribulation, as Jonah was by the heat of the sun, and grieves greatly. Yet the salvation of the pagan and the penitent is considered more important than its grief and the shadow which it loved.”