David reigned over all Israel; and he executed justice and righteousness to all his people.
These verses are parallel with  2 Samuel 8:15-18; and we have written five pages of comments on these verses in that commentary, pp. 108-112.  Special attention is there devoted to the apparent conflict of  1 Chronicles 18:17 here with  2 Samuel 8:18.  It is resolved in the fact that there was an early meaning of the word incorrectly translated "priest," in 2Samuel, which was sometimes used for administrator, which is the office meant in both references.