דברי הימים ב ל:טז פירוש: רש״י

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.