Ira the Jairite - Not mentioned before: perhaps the same as "Ira an Ithrite" (marginal reference), i. e., an inhabitant of Jattir in the hill country of Judah Joshua 15:48; 1-Samuel 30:27. Perhaps we ought to read "Ithrite," for "Jairite."
A chief ruler about David - More simply and clearly, "was David's kohen" (2-Samuel 8:18 note). In the early part oph David's reign his own ons were כהן kôhên (chief rulers). The deaths of Amnon and Absalom, and the dissensions in the family, had probably caused the change of policy in this respect.

Ira - was a chief ruler about David - The Hebrew is כהן לדויד cohen ledavid, a priest to David; and so the Vulgate, Septuagint, Syriac, and Arabic. The Chaldee has רב rab, a prince, or chief. He was probably a sort of domestic chaplain to the king. We know that the kings of Judah had their seers, which is nearly the same: Gad was David's seer, 2-Samuel 24:11, and Jeduthun was the seer of King Josiah, 2-Chronicles 35:16.
The conclusion of this chapter is very similar to the conclusion of 2-Samuel 8:16-18 (note), where see the notes.

And Ira also the Jairite was a (o) chief ruler about David.
(o) Either in dignity or familiarity.

And Ira also the Jairite,.... Which some take to be the same with Ira the Ithrite, 2-Samuel 23:38; a son of Jether or Ithra the Israelite, 2-Samuel 17:25; though others suppose he was Ira the son of Ikkesh the Tekoite, 2-Samuel 23:26; and so the Targum here calls him Ira the Jairite, which was of Tekoah; and Tekoah being the chief place in Israel for oil olive (d), with which the lamps were lighted, Jarchi thinks he had the name of Jairite from Jair, which signifies to enlighten; but rather he was a descendant from Jair the Gileadite, and perhaps was a great friend to David when in Gilead, and from whence he brought him and promoted him: for he
was a chief ruler about David; a prime minister, an intimate friend, the chief of his privy council; perhaps he succeeded Ahithophel; it is much we hear nothing of Hushai.
(d) Misn. Menachot, c. 8. sect. 3.