What shall I render unto Jehovah? He now exclaims with devout admiration, that the multitude of God's benefits was greater than he could find language to give expression to the grateful emotions of his heart. The question is emphatic, What shall I render? and imports, that it was not the desire, but the means, of which he was destitute, to enable him to render thanks to God. Acknowledging his inability, he adopts the only means in his power, by extolling the grace of God as highly as he could. "I am exceedingly wishful to discharge my duty, but when I look around me, I find nothing which will prove an adequate recompense." Some understand the phrase, upon me, to intimate, that David had the recollection of all the benefits which God bestowed on him deeply engraven upon his mind. Others, along with the LXX., supply the particle for, What shall I render unto Jehovah for all his benefits towards me? But it is much better to make the first clause of the verse a complete sentence, by putting a period after Jehovah. Because, after confessing his incompetency, or rather his having nothing to offer to God as a sufficient compensation for his benefits, he at the same time adds in confirmation of it, that he was laid under such obligations, not by one series of benefits only, but by a variety of innumerable benefits. "There is no benefit on account of which God has not made me a debtor to him, how should I have means of repaying him for them?" All recompense failing him, he has recourse to an expression of thanksgiving as the only return which he knows will be acceptable to God. David's example in this instance teaches us not to treat God's benefits lightly or carelessly, for if we estimate them according to their value, the very thought of them ought to fill us with admiration. There is not one of us who has not God's benefits heaped upon us. But our pride, which carries us away into extravagant theories, causes us to forget this very doctrine, which ought nevertheless to engage our unremitting attention. And God's bounty towards us merits the more praise, that he expects no recompense from us, nor can receive any, for he stands in need of nothing, and we are poor and destitute of all things.

What shall I render unto the Lord for all his benefits toward me? - All his "recompences," - the same word which in Psalm 116:7 is rendered "hath dealt bountifully." The question here has reference to that. What return can be equal to his bounties; what will be a proper acknowledgment of them; with what can I repay him for them all? The question is a natural and a proper question. It is one which we naturally ask when we have received a favor from our fellowmortals; how much more proper is it in view of the favors which we receive from God - especially in view of the mercy of God in the gift of a Saviour; the love manifested in the redemption of the soul! What can be an adequate return for love like that - for mercies so great, so undeserved?

What shall I render - מה אשיב mah ashib, "What shall I return?"
For his benefits - תגמולוהי tagmulohi, "His retributions," the returns he had made to my prayers and faith.

What shall I render unto the Lord?.... He considers the Lord only as the author and giver of his mercies, and has nothing to say of his own merits, nor of other persons, who might be instruments of good to him; but is for giving all the glory to God: not as though he could render anything proportional or equivalent to what he had received, but as having a grateful sense of mercies, and willing, to express it; though at a loss, in a great measure, in what manner to do it, and therefore puts this question to himself and others:
for all his benefits towards me; or, "all his benefits are upon me" (m). This being a clause of itself; and shows what moved him to put the question he did; a sense of divine favours was impressed upon him, a load of benefits lay on him, and he wanted to ease himself in expressions of gratitude. These benefits were the blessings of nature and providence; his being, and the preservation of it, food, raiment, &c. and the blessings of grace; spiritual blessings, all things pertaining to life and godliness, sanctification, adoption, pardon, justification, and eternal life. These may well be called "benefits", since they spring entirely from the free grace of God; and they were many, more than could be counted and reckoned up, and set in order before the Lord; and yet he was desirous that none of them might be forgotten, but that praise might be rendered to the Lord for them all.
(m) So Montanus, Junius & Tremellius, Cocceius, Michaelis.

These are modes of expressing acts of worship (compare Psalm 116:4; Psalm 50:14; Jonah 2:9).