The general account here given of Joash is, 1. That he reigned forty years. As he began his reign when he was very young, he might, in the course of nature, have continued much longer, for he was cut off when he was but forty-seven years old, Kg2 12:1. 2. That he did that which was right as long as Jehoiada lived to instruct him, Kg2 12:2. Many young men have come too soon to an estate - have had wealth, and power, and liberty, before they knew how to use them - and it has been of bad consequence to them; but against this danger Joash was well guarded by having such a good director as Jehoiada was, so wise, and experienced, and faithful to him, and by having so much wisdom as to hearken to him and be directed by him, even when he was grown up. Note, It is a great mercy to young people, and especially to young princes, and all young men of consequence, to be under good direction, and to have those about them that will instruct them to do that which is right in the sight of the Lord; and they then do wisely and well for themselves when they are willing to be counselled and ruled by such. A child left to himself brings his mother to shame, but a child left to such a tuition may bring himself to honour and comfort. 3. That the high places were not taken away, Kg2 12:3. Up and down the country they had altars both for sacrifice and incense, to the honour of the God of Israel only, but in competition with, and at least in tacit contempt of, his altar at Jerusalem. These private altars, perhaps, had been more used in the late bad reigns than formerly, because it was not safe to go up to Jerusalem, nor was the temple-service performed as it should have been; and, it may be, Jehoiada connived at them, because some well-meaning people were glad of them when they could not have better, and he hoped that the reforming of the temple, and putting things into a good posture there, would by degrees draw people from their high places and they would dwindle of themselves; or perhaps neither the king nor the priest had zeal enough to carry on their reformation so far, nor courage and strength enough to encounter such an inveterate usage.

Jehoash did - right in the sight of the Lord - While Jehoiada the priest, who was a pious, holy man, lived, Jehoash walked uprightly; but it appears from Ch2 24:17, Ch2 24:18, that he departed from the worship of the true God after the death of this eminent high priest, lapsed into idolatry, and seems to have had a share in the murder of Zechariah, who testified against his transgressions, and those of the princes of Judah. See above, Kg2 11:20-21 (note).

O how few of the few who begin to live to God continue unto the end!

And Jehoash did that which was right in the sight of the Lord all his days,.... Worshipping the only true God, and ruling and walking according to the law of God:

wherein Jehoiada the priest instructed him; and so long as he observed his instructions, and as long as that priest lived, he reigned well; for to that period "all his days must be limited"; for after his death he was seduced by the princes of Judah to idolatry, and lived scandalously, and died ignominiously; see Ch2 24:2.