John Gill Commentary 2 Chronicles 29:15

"And they gathered their brethren, and sanctified themselves, and went in, according to the commandment of the king by the words of Jehovah, to cleanse the house of Jehovah." — 2 Chronicles 29:15 (ASV)

And they gathered their brethren, and sanctified themselves ,
&c.] As they were bid, see (2 Chronicles 29:5) , and came, according to the commandment of the king, by the word of the
Lord, to cleanse the house of the Lord ;
for this, which the king commanded, was by the Lord, and they came to do this work, in obedience to both.