When God said to Abraham, "Walk before Me and be thou perfect," was He taunting him? No. It was the same as the promise He had made to him, "Thou shalt love the Lord thy God with all thy heart and thy neighbor as thyself." The will of God for us, in this life, is that we should walk before him and be perfect in our sphere as He Himself is in His own sphere.
The same word which said to the earth, "Bring forth grass," speaks to us in the words of God's law! The law of His mouth bids us, "Be holy in all your conduct." Has the word of the Lord lost any of its power? No. It lives and abides for ever. 1 Peter 1:25. The wonder of it is, His omnipotent will is expressed in the precepts of His holy law! Rom.2:18.
God's will is omnipotent. When in the beginning He said, "Let there be light! There was light!" It was God's will that there should be light, that the light should shine out of the darkness! He commanded and it stood fast! Ps.33:6,9.
His will is omnipotent! When God said, "Let the earth bring forth grass and herb yielding seed and trees bearing fruit," it was so! Why, because His will is omnipotent! And His will and His good pleasure are one and the same thing: "My word shall accomplish what I please." Isaiah 55:11.
The psalmist says, "I believe Your commandments." Ps.119:65. The only way to keep the commandments of God is by believing them! We are all familiar with Rom.10:17: "Faith comes by hearing and hearing by the word of God." Faith springs up in the heart as we hear the voice of Him whose word can renew the soul unto everlasting life. "I know that His commandment is everlasting life." John 12:50. The commandments of God and the faith of Jesus are inseparable! Rev.14:12.
Why is it that faith comes by hearing the commandments of God? Because the commandments of God are the voice of God speaking to the soul in promise! When we understand that, faith springs up in the heart! "My sheep hear My voice." John 10:27. The ten commandments are the voice of God speaking to the soul in promise. There is not a negative in that law though it may appear thus!
It is the voice of God which we hear in the words of His law! His will is expressed in the precepts of His holy law. His will is omnipotent! Therefore all His biddings are enablings! When we understand that, then we understand that every commandment that proceeds out of the mouth of God is a promise, a most positive promise of its fulfillment. Then it is that faith springs up in our heart, and the creative energy in the word of God is immediately at work, creating in us that which the word speaks! 1 Thess.2:13. And the life which is thus received (Ps.119:50,93; Prov.4:20-22), is in like manner sustained, "by every word that proceeds out of the mouth of God." Matt.4:4.
"Praise His word." Ps.56:4,10.
Then we can exclaim with the psalmist: "I delight to do Thy will, O my God, And Thy law is within my heart." Ps.40:8. "My ears You have opened." verse 6.
Therefore, to believe His commandments is to receive them as they were always meant to be received, as exceedingly great and precious promises by which we may become partakers of the divine nature! 2 Peter 1:4.
Every commandment proceeding out of the mouth of God is a promise. In other words, our life may be bound up with the life of God through the golden chain of the immutable promises of God. Then it is that the commandments become Spirit and life to us. Then it is that the law of His mouth becomes to us the law of the Spirit of life in Christ Jesus! John 6:63,68. "All His promises are Yes and Amen in Christ Jesus to the glory of God through us." 2 Cor.1:20.
Then we can say with Jesus, "I know that His commandment is life everlasting." John 12:50.
Then it is that we can say with the psalmist, "Praise His word." Ps.56:4,10.
Then we understand why he exclaimed, "The law of Your mouth is better to me than thousands of shekels of gold and silver." Ps.119:72.
The prophet Jeremiah certainly understood: "I found your words and I ate them and they were the rejoicing of my heart." Jer.15:16.
"The statutes of the Lord are right, rejoicing the heart." Ps.19:8.
Finally, we may say, "My heart stands in awe of Your word. I rejoice at Your word as one who finds great treasure." Ps.119:161,162. "The reception of the word, the bread that comes down from Heaven, is the reception of Christ Himself." R&H, vol.5, p.227.
P.S. Therefore, unbelief is not believing His commmandments, not believing that they are self-fulfilling because Christ is in them and that He imparts His Spirit to us through them! John 6:63; 2 Cor.3:17.