John Gill Commentary 2 Chronicles 30:12

"Also upon Judah came the hand of God to give them one heart, to do the commandment of the king and of the princes by the word of Jehovah." — 2 Chronicles 30:12 (ASV)

Also in Judah the hand of God was to give them one heart
To make them unanimous in this service, hearty and willing to it, to a man, which was owing to the power and efficacy of divine grace:

to do the commandment of the king and of the princes, by the word of
the Lord ;
to keep the passover, which they did not only in obedience to their superiors, and their orders, but considering these as agreeable to the word and will of God.