For, when strength was made perfect in weakness, it showed the kindness and transcendent power of God.
He patiently suffered Jonah to be swallowed by the whale not that he should be swallowed up and perish altogether.
Rather, He did this so that, having been cast out again, Jonah might be the more subject to God, and might glorify Him the more who had conferred upon him such an unhoped-for deliverance;
and that he might bring the Ninevites to a lasting repentance, so that they should be converted to the Lord, who would deliver them from death, having been struck with awe by that portent which had been wrought in Jonah’s case.
The Scripture says of them, “And they returned each from his evil way, and the unrighteousness which was in their hands, saying, Who knoweth if God will repent, and turn away His anger from us, and we shall not perish?”
So also, from the beginning, did God permit man to be swallowed up by the great whale, who was the author of transgression.
He did so not that man should perish altogether when so engulfed, but He arranged and prepared the plan of salvation, which was accomplished by the Word, through the sign of Jonah.
[...] This was done that man, receiving an unhoped-for salvation from God, might rise from the dead, and glorify God, and repeat that word which was uttered in prophecy by Jonah:
“I cried by reason of mine affliction to the Lord my God, and He heard me out of the belly of hell.”
And it was done so that he might always continue glorifying God, and giving thanks without ceasing, for that salvation which he has derived from Him: “that no flesh should glory in the Lord’s presence.”
[...] For he Satan thus rendered man more ungrateful towards his Creator, obscured the love which God had towards man, and blinded his mind not to perceive what is worthy of God, comparing himself with, and judging himself equal to, God.
This, therefore, was the object of the long-suffering of God: that man,…learning by experience what is the source of his deliverance, may always live in a state of gratitude to the Lord, and that, having obtained from Him the gift of incorruptibility, he might love Him the more.
For “he to whom more is forgiven, loveth more,” and that he may know himself, how mortal and weak he is.
Irenaeus of Lyons (2nd century AD – c. 202): Adversus Haereses, 3,20, 1-2.