Albert Barnes Commentary 2 Chronicles 35:6

"And kill the passover, and sanctify yourselves, and prepare for your brethren, to do according to the word of Jehovah by Moses." — 2 Chronicles 35:6 (ASV)

Prepare your brethren... - that is, “as you minister to your brethren the people, by killing and flaying their offerings and handing the blood to the priests, instruct them how they are to eat the Passover acceptably.” It is implied that many would be ignorant of the requirements of the Law.