"Salvation is from the Lord" (Jonah 2:9). Salvation comes first, then there is service. Before his prayer "from inside the fish" (Jonah 2:1), Jonah was running away from God. He wasn't serving God. Before we can do something for God - serving Him, He must do something for us: He must save us. Jonah's prayer comes from "out of the depths" (Psalm 130:1). In the depths, he finds that "there is forgiveness with God" (Psalm 130:4). With God's forgiveness comes hope for the future (Psalm 130:5,7). This hope comes from God's "faithful love" and His "abundant redemption" (Psalm 130:7).
Jonah's experience was a physical deliverance. He should have been dead. He remained alive. There was more than that. The man who came out of the fish was different from the man who was swallowed by the fish. He had been disobedient. Now, he was obedient - and blessed.