John Gill Commentary 2 Chronicles 24

Ver. 1,2. Joash was seven years old when he began to reign
2 Chronicles 24:2

(See Gill on 2 Chronicles 24:1).

And the chief of the house of the father of the families of
the Kohathites [shall be] Elizaphan the son of Uzziel .
] The same man, who, with his brother Mishael, carried Nadab and Abihu out of the camp, and buried them, (Leviticus 10:4Leviticus 10:5) ; he descended from the last and youngest of the families of the Kohathites; and some think this was one reason at least of Korah's dissatisfaction, and of his entering into a conspiracy against Moses and Aaron, because one of a younger family of his house was preferred to this dignity before him.

And Jehoiada took for him two wives
Not for himself; he had a wife who was aunt to King Joash, and he had sons who were concerned with him in anointing him, (2 Chronicles 22:11) (23:11) and was now upwards of one hundred years of age.

But for the king, when he was at an age fit for marriage, he advised him to marry, and proposed wives to him, whom he thought would be agreeable; for, observing what mischief was done both in church and state through Jehoram's marrying Athaliah, he was desirous of preventing any such disagreeable marriage; and as the young king was in all things guided and directed by him, so he was in this; and no doubt they were good women he pitched upon, and proposed to the king; one of them was Jehoadan, (2 Chronicles 25:1) , but the name of the other we know not:

and he begat sons and daughters ;
how many is not said, nor do we read of the names of any of them, but of Amaziah who succeeded him.

And it came to pass after this
After his marriage, when he was about twenty or twenty one years of age, perhaps:

that Joash was minded to repair the house of the Lord ;
which in some places might be fallen to decay, having been built one hundred and fifty years or more, and in others defaced by Athaliah, and needed ornamenting, see (2 Kings 12:4) .

And he gathered together the priests and Levites
To communicate his mind unto, and give them a charge and instructions:

and said unto them, go out unto the cities of Judah, and gather of all
Israel money to repair the house of your God from year to year ;
what money he means is more fully explained in (2 Kings 12:4) ,

and see that you haste the matter ;
for he was very desirous of having this work accomplished, it being the place of the worship of God, and where he had been preserved in his infancy:

howbeit, the Levites hastened it not ;
either through negligence in them to collect the money, or backwardness in the people to give, or through an avaricious disposition to keep it, and use it for themselves; so that it was delayed unto the twenty third year of his reign (2 Kings 12:6) .