Psalm 119:34 Give me understanding, that I may keep your law and observe it with my whole heart.
I like the burning zeal David has to learn from God what man could not teach him. God has given all human beings a measure of intellectual capacity to think and learn, but here David teaches us that we can ask God to give us grace to use that ability to understand what tends to our peace. He asks to know how to keep God's law. He prays that the Lord must enlighten his mind to understand God's will.
We need wisdom and understanding to keep God's law. Therefore, we also find in the New Testament that the apostle Paul often prays that the Holy Spirit must give the believers enlightened eyes to understand and take possession of our inheritance. He calls the Spirit the Spirit of wisdom and revelation. The Apostle John says: we know that the Son of God has come and has given us understanding, so that we may know him who is true; and we are in him who is true, in his Son Jesus Christ (1 John 5:20).
In this Psalm, David does not ask just for understanding to keep the word. He also prays for grace to observe God's law wholeheartedly. In Hebrew thinking, understanding and knowledge are not anything theoretical and intellectual, but are always linked to life. We only understand God's Word when we live it. If we do not live by the word of God, we have not understood it. If we truly understand who God is and what He says we should do, we would not dare or want to do something other than obey. When we have come to know God through Jesus Christ, we also have the urge to do His will.
There are some translations where this last sentence is not a prayer, but a promise: Truly, I shall observe it with my whole heart! There is no contradiction between its two ways of translating this sentence. Whenever we give a promise to God, we do it in prayer for grace to fulfil it. Whenever we commit ourselves to something for God, we do so in the belief that God will help us. Our prayer and promise go in the same direction. Both are turned to God. It is him we want to learn from. It is His will that we will do, and it is His grace that will help us. We pray wholeheartedly, and will gladly keep and observe His law of our whole heart.
"Give me an understanding heart, that I with burning zeal can know and obey your truth!"