Moshe tells the people of Israel, “You shall cross the Jordan and settle in the land that Hashem … causes you to inherit…” וְהֵנִיחַ לָכֶם מִכָּל אֹיְבֵיכֶם מִסָּבִיב וִישַׁבְתֶּם בֶּטַח, “…and He will give you rest from all your enemies all around, and you will dwell securely.” (Deut. 12,10) If Hashem will give the Israelites peace from the enemies, they will surely live peacefully. Why add those additional words?
Perhaps the reason is that when the country is surrounded by enemies the Israelites would fight among themselves, each one with a different solution as to how to deal with the danger. After the enemies are defeated it will bring peace not only from outside the country but also within. No longer will there be a need for further disputes among the people themselves.
Unfortunately, we are living in Israel today with the same external threats from enemies from without who threaten to destroy us. Among the Jews themselves there are varying opinions as to how we should be dealing with these threats. This is what Moshe was telling our people. There may be disagreements and arguments among the people as to what is the correct approach to our enemies. When they will have been quieted, then וִישַׁבְתֶּם בֶּטַח then you will live peacefully among yourselves.