1. Joshua was to know God’s Word. That is, he was to read it and study it. If the law of Moses was to be Joshua’s guide, as these verses clearly indicate it was, then Joshua would have to know what that law said.
2. Joshua was to talk about God’s Word. The text says, “This Book of the Law shall not depart from your mouth” (v. 8). Clearly, Joshua was to be conversing about the Bible in his normal day-to-day contacts with family, soldiers, friends, and others who were part of the nation.
3. Joshua was to meditate on God’s Word. Meditation is a step beyond mere knowledge of the Scripture or mere talking about it. Meditation implies reasoning about the Word and deducing things from it. Meditation has application as a goal.
4. Joshua was to obey God’s Word in its entirety. The last element in this list of requirements is the most important. Not only was Joshua to know, speak about, and meditate on the law of Moses, he was also and chiefly to obey it. God said, “Being careful to do according to all the law that Moses my servant commanded you. Do not turn from it to the right hand or to the left. . . . Be careful to do according to all that is written in it” (vv. 7–8).

Nearly everybody wants to be prosperous at what he or she is doing, yet most fail. What is the problem? The problem is that we do not follow the divine formula for success that was given to Joshua. According to the Bible, the secret of success is to know God’s Word, speak about it, meditate on it, and then, above all, do it. In God’s world there is no substitute for full obedience.

This was why Joshua was so successful. Joshua was a good soldier, but he was no more brilliant as a commander than countless others who have swept across the battle plains of world history. Joshua was a leader of men, but he was no more gifted at that than many others. Joshua’s great secret was that he made it his job to know the law of God and do it. That is what we need today: not increasingly clever methods, still less increasingly clever people, but obedience informed and motivated by the living and abiding Word of God.