*Minor differences ignored. Grouped by changes, with first version listed as example.
The conspiracy of Zimri - Elah's "servant" (i. e., "subject") - was favored by his position, which probably gave him military authority in the city, by the absence of a great part of the people and of the officers who might have checked him, at Gibbethon 1-Kings 16:15, and by the despicable character of Elah, who, instead of going up to the war, was continually reminding men of his low origin by conduct unworthy of royalty.
Steward - The office was evidently one of considerable importance. In Solomon's court it gave the rank of שׂר śar, prince. In Persia the "steward of the household" acted sometimes as a sort of regent during the king's absence.
Captain of half his chariots - It is probable that Zimri, and some other who is not here named, were commanders of the cavalry.
And his servant Zimri, captain of half [his] chariots, conspired against him, as he was in Tirzah, (e) drinking himself drunk in the house of Arza steward of [his] house in Tirzah.
(e) The Chaldee text has this, "Drinking till he was drunk in the temple of Arza the idol by his house in Tirzah".
And his servant Zimri, captain of half his chariots,.... His military chariots; there were two captains of them, and this was one of them; so the Targum,
"one of the two masters or captains of the chariots:''
conspired against him, as he was in Tirzah drinking himself drunk in the house of Arza, steward of his house in Tirzah; who had the charge of his wine and other liquors, to which he was addicted beyond measure; and this was a fit opportunity for Zimri to fall upon him, and slay him, when he was drunk, and off his guard, and his army at the same time was besieging Gibbethon, 1-Kings 16:15 so that there was a very great likeness in what befell the family of Baasha, to that of the family of Jeroboam; for as the son of the one, and of the other, reigned but two years, so they were both slain by their servants, and both at a time when Gibbethon was besieged; the Targum takes this Arza to be the temple of an idol so called, near the royal palace.
ZIMRI'S CONSPIRACY. (1-Kings 16:9-22)
Zimri . . . conspired against him--"Arza which was over his house." During a carousal in the house of his chamberlain, Zimri slew him, and having seized the sovereignty, endeavored to consolidate his throne by the massacre of all the royal race.
Chariots - Of all his military chariots, and the men belonging to them: the chariots for carriage of necessary things, being put into meaner hands. Tirzah - Whilst his forces were elsewhere employed, 1-Kings 16:15, which gave Zimri advantage to execute his design.
*More commentary available at chapter level.