Then Hezekiah and all the people rejoiced at what God had prepared for the people, because everything had been accomplished so quickly.
The temple being cleansed, we have here an account of the good use that was immediately made of it. A solemn assembly was called to meet the king at the temple, the very next day (Ch2 29:20); and very glad, no doubt, all the good people in Jerusalem were, when it was said, Let us go up to the house of the Lord, Psa 122:1.
Commenting on 2 Chronicles 29:20-36
THE HOUSE OF GOD CLEANSED. (2Ch. 29:12-36) Then the Levites arose--Fourteen chiefs undertook the duty of collecting and preparing their brethren for the important work of cleansing the Lord's house. Beginning with the outer courts--that of the priests and that of the people--the cleansing of these occupied eight days, after which they set themselves to purify the interior; but as the Levites were not allowed...
Commenting on 2 Chronicles 29:12-36
And Hezekiah rejoiced, and all the people, that God had prepared the people: for the thing was [done] suddenly. (r) He shows that religion cannot proceed unless God touches the heart of the people.