Jonah 3 - Matthew Henry's Concise Commentary on the Bible
Jonah sent again to Nineveh, preaches there.
God employs Jonah again in his service. His making use of us is an evidence of his being at peace with us. Jonah was not disobedient, as he had been. He neither endeavoured to avoid hearing the command, nor declined to obey it. See here the nature of repentance; it is the change of our mind and way, and a return to our work and duty. Also, the benefit of affliction; it brings those back to their place who had deserted it. See the power of Divine grace, for affliction of itself would
rather drive men from God, than draw them to him. God's servants must go where he sends them, come when he calls them, and do what he bids them; we must do whatever the word of the Lord commands. Jonah faithfully and boldly delivered his errand. Whether Jonah said more, to show the anger of God against them, or whether he only repeated these words again and again, is not certain, but this was the purport of his message. Forty days is a long time for a righteous God to delay judgments, yet it is
but a little time for an unrighteous people to repent and reform in. And should it not awaken us to get ready for death, to consider that we cannot be so sure that we shall live forty days, as Nineveh then was that it should stand forty days? We should be alarmed if we were sure not to live a month, yet we are careless though we are not sure to live a day. (Jon 3:5-10)