Jonah 2:8,9

Those who regard lying vanities,

Forsake their own mercy,

But I will sacrifice to you with the voice of thanksgiving,

I will pay what I have vowed.

Salvation is of YHWH.”

But he acknowledged that he had been clinging on to deceitful vanities as though he was an idolater (for the phrase compare Psalms 31:6 where it probably refers to idolatry). He had actually believed that he could resign his position as the servant of YHWH and simply walk out on Him, as though YHWH was just an idol. And it had caused him forsake the mercy that was available to him from YHWH. He could hardly believe it of himself. But now all that was past. He was restored to his obedience to YHWH, and once he was in a position to do so he would offer his thanksgiving offering with gratitude, and would pay what he had vowed while he was drowning. For now he recognised in a way that he had not before, that Salvation was of YHWH, totally undeserved and freely given. It had to be for he had just experienced it in that way himself.

‘Salvation is of YHWH.' This is the message of the whole prophecy. It is God Who saves and God alone. And He does it to whomever He will. No one, not even Jonah, could interfere. Once he had learned that lesson he was free to go.