John Gill Commentary 2 Chronicles 35:16

"So all the service of Jehovah was prepared the same day, to keep the passover, and to offer burnt-offerings upon the altar of Jehovah, according to the commandment of king Josiah." — 2 Chronicles 35:16 (ASV)

So all the service of the Lord was prepared the same day
With every sacrifice, and for all sorts of persons:

to keep the passover, and to offer burnt offerings upon the altar of
the Lord ;
which were required to be done on that day:

according to the commandment of King Josiah ;
which was, that every thing be provided, prepared, and done, as the law required.