Jonah 2:1 - Joseph Benson’s Commentary on the Old and New Testaments

Then Jonah prayed Those devout thoughts and feelings which he had at that time, he afterward digested into the following prayer, and added a thanksgiving for his deliverance at the end of it. So several of David's Psalms were probably composed after his trouble was over; but in a manner suitable to the thoughts he had at the time of his affliction; and with a grateful sense of God's mercies for his deliverance out of it: see Psalms 54. and 120. And he heard me He thanks God that, in consequence of his prayer, his life is wonderfully preserved. Out of the belly of hell cried I The word שׁאול signifies the state of the dead. So it may most properly be rendered the grave here, as the margin reads: the belly of the fish was to Jonah instead of a grave.