Israel was on the threshold of the land, and was to take possession of it in obedience to the command of the God of Israel's fathers, the patriarchs. Accomplishing this task would require strength and courage, and so Moses' words ended with a call for Israel not to fear or be dismayed.
21 See, the LORD your God has set the land before you. Go up, take possession, as the LORD, the God of your fathers, has told you. Do not fear or be dismayed.’