A conspiracy - Compare the marginal reference Joash, either from a suspicion of intended treason, or from some other unknown cause, took up his abode in the fortress of Millo 1 Kings 9:24. This conspiracy was connected with religion. Soon after the death of Jehoiada, Joash had apostatised; had renewed the worship of Baal; and, despite of many prophetic warnings, had persisted in his evil courses, even commanding Zechariah to be slain when he rebuked them 2 Chronicles 24:18-27. The conspirators, who wished to avenge Zechariah, no doubt wished also to put down the Baal worship. In this it appears that they succeeded. For, though Amaziah punished the actual murderers after a while 2 Kings 14:5, yet he appears not to have been a Baal-worshipper. The only idolatries laid to his charge are the maintenance of the high places 2 Kings 14:4, and a worship of the gods of Edom 2 Chronicles 25:14-20.

Silla - This place is quite unknown.

The house of Millo - Was a royal palace, built by David; (see 2 Samuel 5:9); and Silla is supposed to be the name of the road or causeway that led to it. Millo was situated between the old city of Jerusalem, and the city of David.

And his servants arose,.... This was after he had slain Zechariah the son of Jehoiada, who reproved him for his idolatry; and after a second expedition of the king of Syria, who came to Jerusalem, and spoiled it, and left Jehoash diseased, as is recorded in 2 Chronicles 24:23,

and made a conspiracy; not to get the kingdom into their hands, for his son succeeded him, but to avenge the death of Zechariah:

and slew Jehoash in the house of Millo, which goeth down to Silla; these are both names of places; perhaps the latter is mentioned, to distinguish this Bethmillo from Millo in Zion; or rather that itself is meant, and described by the descent from it to a causeway, as Silla may signify, which led to the royal palace.

And his servants arose, and made a conspiracy, and {k} slew Joash in the house of {l} Millo, which goeth down to Silla.

(k) Because he had put Zachariah the son of Jehoiada to death, 2Ch 24:25.

(l) Read 2Sa 5:9.

12:20 And slew Joash - We are told, in the Chronicles, that his murdering the prophet, Jehoiada's son, was the provocation. In this, how unrighteous so ever they were, yet the Lord was righteous. And this was not the only time, that he let even kings know, it was at their peril, if they touched his anointed, or did his prophets any harm. Thus fell Joash, who began in the spirit, and ended in the flesh. And indeed God usually sets marks of his displeasure upon apostates, even in this life.

the house...: or, Bethmillo

20. his servants arose . and slew Joash in the house of Millo-(See on [339]2Ch 24:25).

12:17-21 Let us review the character of Jehoash, and consider what we may learn from it. When we see what a sad conclusion there was to so promising a beginning, it ought to make us seek into our spiritual declinings. If we know any thing of Christ as the foundation of our faith and hope, let us desire to know nothing but Christ. May the work of the blessed Spirit on our souls be manifest; may we see, feel, and be earnest, in seeking after Jesus in all his fulness, suitableness, and grace, that our souls may be brought over from dead works to serve the living and true God.