Charles Ellicott Commentary 2 Chronicles 30:15

"Then they killed the passover on the fourteenth [day] of the second month: and the priests and the Levites were ashamed, and sanctified themselves, and brought burnt-offerings into the house of Jehovah." — 2 Chronicles 30:15 (ASV)

And the priests and the Levites were ashamed, and sanctified themselves. —Ashamed of their former reluctance to purify themselves from the defilement contracted by their connection with illegal cults and sanctuaries during the late reign (2 Chronicles 29:34; and 2 Chronicles 30:3, as noted above). In the former passage, the Levites are favourably contrasted with the priests; here they are spoken of in the same terms, a verbal inaccuracy apparently due to the writer’s desire to be brief.