Leviticus 21-22  

Leviticus 21-22 provided special instructions for the priests. Leviticus 18-20 were addressed to the entire congregation of Israel and dealt mostly with holiness in everyday life. Since Israel as a whole is set apart for the Lord (=holy) to be a holy nation, chapters 18-20 detailed some of the ways they had to be distinct and different from the nations personally, socially, and ritually. 

But here in Leviticus 21-22 we shift to the priests. Since they are set apart as a special holy class within the nation, these chapters describe some of the ways hey had to be distinct and different from the rest of Israel. 

So these chapters record what might be called “priestly holiness.”