Jonah 2:8

8 They who hold to false vanities Forsake their own mercy. 9 But I will sacrifice to Thee with the call of thanksgiving. I will pay what I have vowed. Salvation is with Jehovah. In order to express the thought emphatically, that salvation and deliverance are only to be hoped for from Jehovah the living God, Jonah points to the idolaters, who forfeit their mercy. משׁמּרים הבלי־שׁוא is a reminiscence of Psa 31:7. הבלי־שׁוא, worthless vanities, are all things which man makes into idols or objects of trust. הבלים are, according to Deu 32:21, false gods or idols. Shâmar, to keep, or, when applied to false gods, to keep to them or reverence them; in Hos 4:10 it is also applied to Jehovah. חסדּם signifies neither pietatem suam nor gratiam a Deo ipsis exhibitam, nor "all the grace and love which they might receive" (Hitzig); but refers to God Himself, as He whose government is pure grace (vid., Gen 24:27), and might become the grace even of the idolatrous. Jonah, on the contrary, like all the righteous, would sacrifice to the Lord beqōl tōdâh, "with the voice or cry, of thanksgiving," i.e., would offer his sacrifices with a prayer of sincere thanksgiving (cf. Psa 42:5), and pay the vow which he had made in his distress (cf. Psa 50:14, Psa 50:23). These utterances are founded upon the hope that his deliverance will be effected (Hitzig); and this hope is based upon the fact that "salvation is Jehovah's," i.e., is in His power, so that He only can grant salvation.

2:8-9 The conclusion to Jonah’s psalm-prayer bears similarity to 1:16: The sailors also responded to the Lord’s power to save and acts of mercy with sacrifices and vows.