Read Deuteronomy 4:1, 2. What was the specific warning that the Lord gave them in regard to His “statutes and judgments,” and why would this be something that right away they are warned about? (See also Deut. 12:32)

 The Lord tells them to obey the “statutes and judgments” and not to add or take away from them. Why say that? After all, why would anyone want to change God’s law?

 We know the answer, of course.

 “Satan has been persevering and untiring in his efforts to prosecute the work he began in heaven, to change the law of God. He has succeeded in making the world believe the theory he presented in heaven before his fall, that the law of God was faulty, and needed revising. A large part of the professed Christian church, by their attitude, if not by their words, show that they have accepted the same error.” — Ellen G. White, Selected Messages, Book 2, p. 107.

 When you think about the history of ancient Israel, you see that in many ways they got in trouble because not only would they ignore certain precepts of the law, which for all practical purposes was taking away from the law, but they would add to it, in the sense of bringing in practices that were not specified in the law and that, in fact, led ultimately to transgressing it.

 Read Matthew 15:1-9. How do we see an example here of the principle that, though in another context, Moses warned the children of Israel about?
 When the Hebrews eventually got the land promised them, they would often ignore the direct warnings about, for instance, idolatry. As a result, they followed many pagan practices, sometimes even as part of their supposed worship of Yahweh. By the time of Jesus, however, they had added all sorts of human traditions that, as Jesus Himself said, made “the commandment of God of none effect.”
 Either way, adding or taking away, the law was changed, and the nation suffered the consequences.