John Calvin Commentary Psalms 119:112

"I have inclined my heart to perform thy statutes For ever, even unto the end. SAMEKH." — Psalms 119:112 (ASV)

I have inclined my heart to perform thy statutes. In this verse he describes the right observance of the law, which consists in our cheerfully and heartily preparing ourselves for doing what the law commands. Slavish and constrained obedience differs little from rebellion. The prophet, therefore, in order to briefly define what it is to serve God, asserts that he applied not only his hands, eyes, or feet to keeping the law, but that he began with the affection of the heart.

Instead of the verb incline, the verb extend could properly be used; but I am inclined to accept the more generally received interpretation, which is that he devoted himself with sincere affection of heart to the observance of the law. This inclination of the heart is opposed to the wandering lusts which rise up against God and drag us anywhere rather than incline us to a virtuous life.

The attempt of the Papists to defend from this passage their doctrine of free will is mere trifling. They infer from the words of the prophet that it is in the power of man to bend his own heart in whatever way he pleases. But the answer is easy. The prophet does not here boast of what he had done by his own strength, for he now repeats the very same word which he had employed before, when he said, Incline my heart to these testimonies. If that prayer was not insincere, he doubtless acknowledged by it that it was the distinctive work of the Holy Spirit to incline and frame our hearts to God. But it is no new thing for that to be ascribed to us which God works in us; Paul’s statement to this effect is very plain:

It is God who worketh in you, both to will and to do of his good pleasure (Philippians 2:13).

When the prophet says of himself that he inclined his heart, he does not separate his own effort from the grace of the Holy Spirit, by whose inspiration he has previously declared that this was entirely done. At the same time, he distinguishes the constancy of his pious affection from the fleeting zeal of others. Thus, so that he might not fail in the middle of his course, or even turn back, he affirms that he had resolved to continue in the same course throughout his entire life. The word עקב, ekeb, to the end, in my opinion, is added to the word לעולם, leolam, for ever, by way of explanation; and to show us that he struggled courageously against all obstacles and difficulties, so that they would not break his constancy. For no one perseveres in the service of God without strenuous efforts. Some take the word as denoting a reward; but this seems too inconsistent with the purpose of the passage.