Charles H. Spurgeon on Psalms 119:156

This verse is exceedingly like verse one hundred and forty nine, and yet it is no vain repetition. There is such a difference in the main idea that the one verse stands out distinct from the other. In the first case he mentions his prayer, but leaves the method of its accomplishment with the wisdom or judgment of God; while here he pleads no prayer of his own, but simply the mercies of the Lord, and begs to be quickened by judgments rather than to be left to spiritual lethargy. We may take it for granted that an inspired author is never so short of thought as to be obliged to repeat himself: where we think we have the same idea in this psalm we are misled by our neglect of careful study. Each verse is a distinct pearl. Each blade of grass in this field has its own drop of heavenly dew.

Great are thy tender mercies, O LORD. Here the Psalmist pleads the largeness of God's mercy, the immensity of his tender love; yea, he speaks of mercies mercies many, mercies tender, mercies great; and with the glorious Jehovah he makes this a plea for his one leading prayer, the prayer for quickening. Quickening is a great and tender mercy; and it is many mercies in one. Shall one so really good permit his servant to die? Will not one so tender breathe new life into him? "Quicken me according to thy judgments." A measure of awakening comes with the judgments of God; they are startling and arousing; and hence the believer's quickening thereby. David would have every severe stroke sanctified to his benefit, as well as every tender mercy. The first clause of this verse may run, "Many, "or, "manifold are thy compassions, O Jehovah." This he remembers in connection with the "many persecutors" of whom he will speak in the next verse. By all these many mercies he pleads for enlivening grace, and thus he has many strings to his bow. We shall never be short of arguments if We draw them from God himself, and urge both his mercies and his judgments as reasons for our quickening.