1. Trust God and pray for his work (12-17)
God was not going to back down on his judgment against Moses. Moses may have done a million good things, but not honoring God as holy before the people was enough to keep him out of the Promised Land. Moses accepted God's pronouncement and concerned himself with the advancement of God's plan, specifically that a leader be raised up to lead the people.
2. God establishes leaders (18-23)
God told Moses to appoint Joshua as the next leader. The people needed to have confidence in Joshua's leadership. Thus there was a commissioning ceremony led by Eleazar the High Priest. The people would rally around Joshua and Eleazar. God establishes his leaders.