Deuteronomy 7

The chapter goes over what the people are to do to the people currently living in the promised land, and how God was going to do it. (Hittites, Girgashites, Amorites, Canaanites, Perizzites, Hivites, and Jebusites)

The people needed to remain faithful to God's instructions and the blessings would be immense! The people in the land were worshiping false gods and were to be full removed from the land, not intermarried.

If you notice, Ruth was from Moab, not mentioned in the peoples who were to be eradicated.