The Psalm of Thanksgiving (Ch. 2). 

        This psalm is usually regarded as a later insertion. We agree that superficially at least the psalm is so incongruous, that its later insertion seems hardly reasonable. When, however, we grasp that Jonah is thanking God for saving him from drown­ing — hence the language of ver. 5f — which was for him a guarantee of God’s forgiveness and ultimate deliverance, the psalm drops into place as entirely congruous. Even a land­lubber like Jonah knew that this was no ordinary fish.

        As regards the language of the psalm, there are no direct quotations of other psalms, but rather echoes. Modern research has shown that the psalm of thanksgiving largely conformed to stock patterns, so such echoes are not surprising, especially if Jonah, as was very likely the case, was attached to a sanctuary, where he may often have put together such psalms for the worshippers.