Give me understanding, that I may observe Your law And keep it with all my heart.
NASB95
Give me understanding, that I may keep your law and observe it with my whole heart.
ESV
Give me understanding, and I shall keep thy law; yea, I shall observe it with my whole heart.
KJV

'He who is his own teacher'—says Bernard—and one greater than Bernard, 'has a fool for his master.' Man cannot teach what he does not know; and of God, and of His law, he knows nothing. Therefore the beginning of wisdom is a consciousness of ignorance, a distrust of our own understanding, and the heartfelt prayer, "Give me understanding." The spiritual understanding is the gift of Jesus Christ. He directs us to Himself, as its fountain, "I am the light of the world; he who follows Me shall not walk in darkness, but shall have the light of life." This understanding differs from mere intellectual discernment or speculative knowledge. It is the spring of spiritual activity in our walk with God; so that our obedience is not outward and reluctant, but filial delight and wholeness of heart:—we desire not only to keep the law of God to the end, but every day to the end, "with our whole heart."—Such are our obligations towards Him, that we ought to study very accurately the character of our walk with Him; always remembering that service without the heart—the whole heart—is hateful in His sight; and that what is now wilfully withheld, will gradually draw away the rest in apostasy from Him. Now are we seeking more "engagedness of heart" for Him? Then will this prayer be a suitable expression of our need, and the utterance of a humble, resolute petitioner. It is not, however, enough, that we have once received, unless we are constantly receiving. We must ask, that we may receive; but after we have received, we must ask again. Yet is this prayer never offered up, until the soul has in part received what it is here seeking for. The natural man is "wise in his own conceit," and has therefore no idea of his need of Divine teaching.

But we must not be satisfied with even a clear apprehension of the doctrines of the Bible, and of the "truth as it is in Jesus." "Give me understanding"—'not only that I may believe these doctrines, but that I may keep and observe them.' In every path of duty, this cry is repeated, with an importunity that is never wearisome to the ears of our gracious Father. And in how many unnoticed instances has the answer been given, when some clear and heavenly ray has darted unexpectedly into the mind, or some providential concurrence of unforeseen circumstances has disentangled a path before intricate and involved, and marked it before us with the light of a sunbeam! How many whispers of conscience! how many seasonable suggestions in moments of darkness and perplexity, may the observant child of God record, as the answer to this needful prayer! "Whoever is wise, and will observe these things, even they shall understand the loving-kindness of the Lord." Nor will our growth in spiritual understanding fail to evidence itself in the steady consistency of a well-ordered conversation! "Who is a wise man, and endued with knowledge among you? Let him show out of a good conversation his works with meekness of wisdom." If then knowledge is valuable according to its usefulness, one ray of this practical knowledge—the result of prayer for heavenly teaching—is more to be prized than the highest attainments of speculative religion—flowing from mere human instruction.

"Give me understanding, and I shall keep your law." This is the same prayer enlarged, or rather it is a supplement which intensifies it. He not only needs teaching, but the power to learn: he requires not only to understand, but to obtain an understanding. How low has sin brought us; for we even lack the faculty to understand spiritual things, and are quite unable to know them until we are endowed with spiritual discernment! Will God in very deed give us understanding? This is a miracle of grace. It will, however, never be wrought upon us until we know our need of it; and we shall not even discover that need until God gives us a measure of understanding to perceive it We are in a state of complicated ruin, from which nothing but manifold grace can deliver us. Those who feel their folly are by the example of the Psalmist encouraged to pray for understanding: let each man by faith cry, "Give me understanding." Others have had it, why may it not come to met It was a gift to them; will not the Lord also freely bestow it upon met

We are not to seek this blessing that we may be famous for wisdom, but that we may be abundant in our love to the law of God. He who has understanding will learn, remember, treasure up, and obey the commandment of the Lord. The gospel gives us grace to keep the law; the free gift leads us to holy service; there is no way of reaching to holiness but by accepting the gift of God, If God gives, we keep; but we never keep the law in order to obtaining grace. The sure result of regeneration, or the bestowal of understanding, is a devout reverence for the law and a resolute keeping of it in the heart. The Spirit of God makes us to know the Lord and to understand somewhat of his love, wisdom, holiness, and majesty; and the result is, that we honor the law and yield our hearts to the obedience of the faith.

Matthew Henry wisely notes that "an enlightened understanding is that which we are indebted to Christ for; for 'the Son of God is come, and has given us an understanding' " (1 John v. 20). Any writer can give us something to understand, but only the Lord Jesus can give to us understanding itself.

"Yes, I shall observe it with my whole heart." The understanding operates upon the affections; it convinces the heart of the beauty of the law, so that the soul loves it with all its powers; and then it reveals the majesty of the lawgiver, and the whole nature bows before his supreme will. An enlightened judgment heals the divisions of the heart, and bends the united affections to a strict and watchful observance of the one rule of life. He alone obeys God who can say, "My Lord, I would serve you, and do it with all my heart"; and none can truly say this until they have received as a free grant the inward illumination of the Holy Spirit. To observe God's law with all our heart at all times is a great grace, and few there be that find it; yet it is to be had if we will consent to be taught of the Lord.

Look backward and observe the parallel to this verse in verses 2 and 10, where the whole heart is spoken of in reference to seeking, and then look forward to the like parallel in verse 58 in pleading, for mercy; these are all second verses in their octonaries. The frequent repetition of the phrase whole heart shows the importance of undivided love: the heart is never whole or holy until it is whole and wholly united in the fear of the Lord. The heart is never one with God until it is one within itself, and it is never one with itself until it is at one with God.