The book of Joshua starts with God appointing Joshua as leader over the Israelites. Joshua then gives his first command and reminds the two and a half tribes of their promise to Moses.
God appoints Joshua to succeed Moses and blesses him
In Deuteronomy 31:7-8, Moses, in front of all of Israel, had appointed Joshua as his successor. Now, after the death of Moses, God speaks to Joshua in confirmation of this. God instructs him to take the Israelites over the Jordan and repeats the promise that He had made to the Israelites about them possessing Cannan.
God commissions Joshua by blessing him and tells him that he will only succeed in his new role by obeying the law that God had given through Moses because the law is just. There is no higher standard of justice or righteousness than the word of God.
Joshua, by faith, assumes command
After God has spoken to him, Joshua demonstrates his faith by doing what God has told him to do. He instructs the Israelites to prepare to cross the Jordan in the next three day. Once we have read or heard God’s word, obedience is the only sign of faith that we can show and it is the only thing that is required of us.
The Reubenites, the Gadites, and the half-tribe of Manasseh are reminded of their promise
The chapter concludes with Joshua reminding the two and a half tribes of their promise to Moses and they promise Joshua their allegiance.
Just to recap, in Numbers 32, the two and a half tribes requested to be allowed to settle in Gilead and Moses agreed to their request after they gave the following promise. In Numbers 32:16-19 the scriptures say, “And they came near unto him, and said, We will build sheepfolds here for our cattle, and cities for our little ones: But we ourselves will go ready armed before the children of Israel, until we have brought them unto their place: and our little ones shall dwell in the fenced cities because of the inhabitants of the land. We will not return unto our houses, until the children of Israel have inherited every man his inheritance. For we will not inherit with them on yonder side Jordan, or forward; because our inheritance is fallen to us on this side Jordan eastward.“