The word translated “walk” is halakhah in Hebrew. Israel had to walk "in the way."
The Interpreter's Dictionary of the Bible, Volume 2, reads under "Judaism":
The authoritative Jewish way of life as expressed in moral law and ritual precept. It embraces the whole body of Jewish teaching, legislation, and practices that proceeded from interpretation and reinterpretation of the laws of the Bible. . . . Although legalistic in content, the Halakhah is designed to bring all human occupations into relationship to the service of God and to establish the supremacy of the divine will as the measure of all directions and strivings of human life.
On the surface, this sounds good; we should search and meditate as to how the Scriptures apply to every aspect of life. However, these interpretations were merely human opinions. Some of them were right on, but others were grossly off the mark. The Halakhah was not the Word of God.
Over the centuries, the Jews first gradually elevated these interpretations to be equal with Scripture, and then to be more important than Scripture. Mark 7:3 describes such a tradition that did not come from God's law but from Halakhah. Jesus says that they rejected the commandments of God so that they might keep their own tradition (verse 7). He also said their traditions destroyed the effect of God's Word (Mark 7:13). Halakhah was their tradition—the Jewish way of life.
In addition, not only were they zealous in collecting these interpretations and putting them into books, but in their zeal, they encouraged each other to live rigidly according to these interpretations. They were also zealous in proselytizing. Jesus says in Matthew 23 that they would encompass land and sea in order to gain one proselyte, and then they would make him a child of hell.
It became a major problem for Jesus and the church when the Jews did not have the humility to admit that many of their interpretations were wrong. They did not agree with God's Word, and they viewed Jesus, and then the church, as enemies to be obliterated.
Halakhah, the Jewish way of life that Paul called "the traditions of my fathers" in Galatians 1:14, had been his religion. It was in question in the book of Galatians, not the law of God. It was the Jewish way of life, the Halakhah, with ascetic, demon-driven Gnosticism added to it. This was the yoke of bondage that could not be borne.
John W. Ritenbaugh
The Covenants, Grace, and Law (Part 25)
Other Forerunner Commentary entries containing Exodus 18:20: