The priests and Levites were purified together Hebrew, כאחד, cheechad, as one man, so the word signifies. They were unanimous, both in their resolutions, and in their endeavours, to make and keep themselves ceremonially clean for this solemnity: and they joined together in their preparations, that they might help one another; so that all of them were legally pure, and, in this respect, excelled the priests and Levites in Hezekiah's time, who were many of them under blame for not purifying themselves according to the law. The purity of ministers adds much to the beauty and honour of their ministrations, as doth their unity also.
Related Commentaries of Ezra 6:20
Ezra 6:20
20 For the priests and the Levites were purified together, all of them were pure, and killed the passover for all the children of the captivity, and for their brethren the priests, and for themselves.