Be strong and courageous! For you will lead these people to inherit the land I swore to their fathers to give them.
Joshua 1:6

Joshua and Moses began the process of causing Israel to inherit the Land. Yeshua will complete it.

The phrase "Be strong and courageous" is spoken 4 times in Joshua 1. Four is symbolic of the whole world or the entirety of anything. Be strong and courageous in everything because God is with the faithful no matter where they go.