וַיַּֽעַמְד֤וּ עַל־עָמְדָם֙ כְּמִשְׁפָּטָ֔ם כְּתוֹרַ֖ת מֹשֶׁ֣ה אִישׁ־הָאֱלֹהִ֑ים הַכֹּֽהֲנִים֙ זֹרְקִ֣ים אֶת־הַדָּ֔ם מִיַּ֖ד הַלְוִיִּֽם׃
And they stood in their place after their order, according to the law of Moses the man of God; the priests dashed the blood, which they received of the hand of the Levites.
Rashi on II Chronicles
the priests sprinkled For [the rituals] from the reception [of the blood] and onwards are the commandments of the priests, and do not wonder why the owners themselves did not slaughter [the sacrifices], as is explained further: for there were many among the congregation who had not consecrated themselves and the Levites presided over the slaughter of their Passover sacrifices.