While the account of Rahab has more action, it is God’s instruction to Joshua that stands out:
Joshua 1:8-9 Study this Book of Instruction continually. Meditate on it day and night so you will be sure to obey everything written in it. Only then will you prosper and succeed in all you do. This is my command—be strong and courageous! Do not be afraid or discouraged. For the Lord your God is with you wherever you go.
This is similar to the guidelines for kings in keeping justice, who were instructed to read the same ‘body of instruction’ every day:
Deuteronomy 17:19-20 … so that he may learn to revere the Lord his God and follow carefully all the words of this law and these decrees and not consider himself better than his fellow Israelites and turn from the law to the right or to the left. Then he and his descendants will reign a long time over his kingdom in Israel.
And it is a reminder of Moses’ last words to the Israelites, in which he made it clear that obedience comes from the heart.
As for us, we are told that faith comes by hearing, and hearing by the word of God.