The privileged position of the people of Israel compared to other nations is put into words here.
See also Deuteronomy 4:8. How wonderful it is that, thanks to God’s revelation, you do not have to grope blindly like a mole for the truth. Compare this with Romans 10:8. This gives us all the more reason to do what the psalm ends with: Praise the Lord!
20 He has not dealt thus with any other nation; they do not know his rules. Praise the LORD!