John Gill Commentary 2 Chronicles 35:10

"So the service was prepared, and the priests stood in their place, and the Levites by their courses, according to the king`s commandment." — 2 Chronicles 35:10 (ASV)

So the service was prepared
Every thing was got ready both for the passover and the feast of unleavened bread, for all sorts of people, rich and poor:

and the priests stood in their place ;
in their court near the altar, to sprinkle the blood of the sacrifices about it, as in the following verse:

and the Levites in their courses ;
whose turn it was to officiate:

according to the king's commandment ,
(2 Chronicles 35:4) .