A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
2 Chronicles 30:1
ch2 30:1HEZEKIAH PROCLAIMS A PASSOVER. (Ch2 30:1-12)
Hezekiah sent to all . . . Judah . . . to come to . . . Jerusalem, to keep the passover--This great religious festival had not been regularly observed by the Hebrews in their national capacity for a long time because of the division of the kingdom and the many disorders that had followed that unhappy event. Hezekiah longed extremely to see its observance revived; and the expression of his wishes having received a hearty response from the princes and chief men of his own kingdom, the preparatory steps were taken for a renewed celebration of the national solemnity.
letters also to Ephraim and Manasseh--The names of these leading tribes are used for the whole kingdom of Israel. It was judged impossible, however, that the temple, the priests, and people could be all duly sanctified at the usual time appointed for the anniversary, namely, the fourteenth day of the first month (Nisan). Therefore it was resolved, instead of postponing the feast till another year, to observe it on the fourteenth day of the second month; a liberty which, being in certain circumstances (Num 9:6-13) granted to individuals, might, it was believed, be allowed to all the people. Hezekiah's proclamation was, of course, authoritative in his own kingdom, but it could not have been made and circulated in all the towns and villages of the neighboring kingdom without the concurrence, or at least the permission, of the Israelitish sovereign. Hoshea, the reigning king, is described as, though evil in some respects, yet more favorably disposed to religious liberty than any of his predecessors since the separation of the kingdom. This is thought to be the meaning of the mitigating clause in his character (Kg2 17:2).
2 Chronicles 30:6
ch2 30:6the posts--that is, runners, or royal messengers, who were taken from the king's bodyguard (Ch2 23:1-2). Each, well mounted, had a certain number of miles to traverse. Having performed his course, he was relieved by another, who had to scour an equal extent of ground; so that, as the government messengers were despatched in all directions, public edicts were speedily diffused throughout the country. The proclamation of Hezekiah was followed by a verbal address from himself, piously urging the duty, and setting forth the advantages, of a return to the pure faith and institutions which God had delivered to their ancestors through Moses.
the remnant of you, that are escaped out of the hand of the kings of Assyria--This implies that several expeditions against Israel had already been made by Assyrian invaders--by Pul (Kg2 15:19), but none of the people were then removed; at a later period by Tiglath-pileser, when it appears that numbers among the tribes east of Jordan (Ch1 5:26), and afterwards in the northern parts of Israel (Kg2 15:20), were carried into foreign exile. The invasion of Shalmaneser cannot be alluded to, as it did not take place till the sixth year of Hezekiah's reign (Kg2 17:6; Kg2 18:9-12).
2 Chronicles 30:10
ch2 30:10the posts passed from city to city--It is not surprising that after so long a discontinuance of the sacred festival, this attempt to revive it should, in some quarters, have excited ridicule and opposition. Accordingly, among the tribes of Ephraim, Manasseh, and Zebulun, Hezekiah's messengers met with open insults and ill usage. Many, however, in these very districts, as well as throughout the kingdom of the ten tribes, generally complied with the invitation; while, in the kingdom of Judah, there was one unanimous feeling of high expectation and pious delight. The concourse that repaired to Jerusalem on the occasion was very great, and the occasion was ever after regarded as one of the greatest passovers that had ever been celebrated.
2 Chronicles 30:14
ch2 30:14THE ASSEMBLY DESTROYS THE ALTARS OF IDOLATRY. (Ch2 30:13-27)
they arose and took away the altars that were in Jerusalem--As a necessary preparation for the right observance of the approaching solemnity, the removal of the altars, which Ahaz had erected in the city, was resolved upon (Ch2 28:24); for, as the people of God, the Hebrews were bound to extirpate all traces of idolatry; and it was a happy sign and pledge of the influence of the Spirit pervading the minds of the people when they voluntarily undertook this important preliminary work.
2 Chronicles 30:15
ch2 30:15the priests and the Levites were ashamed--Though the Levites are associated in this statement, the priests were principally referred to; those of them who had been dilatory or negligent in sanctifying themselves (Ch2 29:34) were put to the blush and stimulated to their duty by the greater alacrity and zeal of the people.
2 Chronicles 30:16
ch2 30:16the priests sprinkled the blood, which they received of the hand of the Levites--This was a deviation from the established rules and practices in presenting the offerings of the temple. The reason was, that many present on the occasion having not sanctified themselves, the Levites slaughtered the paschal victims (see on Ch2 35:5) for everyone that was unclean. At other times the heads of families killed the lambs themselves, the priests receiving the blood from their hands and presenting it on the altar. Multitudes of the Israelites, especially from certain tribes (Ch2 30:18), were in this unsanctified state, and yet they ate the passover--an exceptional feature and one opposed to the law (Num 9:6); but this exception was allowed in answer to Hezekiah's prayer (Ch2 30:18-20).
2 Chronicles 30:20
ch2 30:20the Lord . . . healed the people--We imagine the whole affair to have been the following: In consequence of their transgressions they had cause to fear disease and even death (Lev 15:31). Hezekiah prayed for the nation, which was on the point of being diseased, and might therefore be regarded as sick already [BERTHEAU].
2 Chronicles 30:21
ch2 30:21the children of Israel . . . kept the feast--The time appointed by the law for the continuance of the feast was seven days [Exo 12:15; Exo 13:6; Lev 23:6]; but in consequence of its having been allowed to fall so long into desuetude, they doubled the period of celebration and kept it fourteen days with unabated satisfaction and joy. Materials for the additional sacrificial meals were supplied by the munificence of the king and the princes.
2 Chronicles 30:24
ch2 30:24and a great number of priests sanctified themselves--so that there would be a sufficient number of hands for the additional services.