Learning to depend on God.
v1-3: Although Moses was a great man, and had been respected as such, it was more important that the people trust God, and know that He would cross the Jordan with them. The new leader, taking over from Moses, was to be Joshua. And although human leaders change, our divine leader cannot change, and always remains.
v4-5: Just as God had given victory against Sihon and Og, Kings of the Amorites, so He would give victory against the Canaanite peoples.
v6: The people had simply to trust in God. God would remain faithful to His people.
v7-8: Having addressed the people, Moses spoke also to Joshua, that he might be strong, and trust in God, knowing God's presence; compare Josh 1.6-9. Leaders and people (v6) must be equally courageous.
Joshua had the extra responsibility to "go with this people", for through him they would inherit the land of Canaan. The leader cannot be apart from his people; he must be among them.
v9: Moses had the law written down. See 2 Chr 34.14-15, where the priests found the Book of the Law.
v10-13: The priests and elders had to ensure that the law of God was taught to the people. Every seven years time had to be set aside for the reading of the law. This was not the only time when the law was read and explained, since each household had the same responsibility, Ex 13.8,14.
Thus, obedience and commitment was not just for leaders, but for all.
v14-15: The choice of Joshua as the next leader was God's choice.
v16: Future rebellion was predicted, but not excused. Moses knew that the people still did not have a heart to love God.
v17-18: Their rebellion would be serious, and God would punish them.
v19: The song of Moses (ch 32) was to be taught to the people, as a witness against them, also v22.
v20: Once the people were settled in the land, and beginning to prosper, then they would depart from the true God; see 32.15.
v21: The Lord knew their hearts (29.4), and that they were not truly devoted to Him. He knew their secret rebellion.
v23: The Lord gave encouragement to Joshua. There is little detail as to how he was inaugurated as leader. Part of the process was the preparation of the people, as well as Joshua himself.
v26-27: The law of God itself was another testimony of the people's rebellion. Like the manna, the tablets of stone, and Aaron's rod, each speak of their rebellion against God.
v29: After Moses' death, he predicted, they would depart from the Lord, and would suffer the consequences, see v17, 21.
v30: The song of Moses was recited and taught to the whole people.