2 Chronicles 30:18 - Joseph Benson’s Commentary on the Old and New Testaments

A multitude of the people had not cleansed themselves Either they did not know, after such a long night of ignorance and superstition, what ceremonies were required, in order to their purification, or they had not time to use them. Yet having an eager and pious desire to commemorate their wonderful deliverance out of the Egyptian bondage, they were permitted, in their uncleanness, to eat the passover, lest they should be discouraged if they were denied it, in this their return to the true religion. But Hezekiah prayed for them It was his zeal that had called them together in such haste, and he would not that they should fare the worse for being straitened for time in their preparation. He therefore thought himself concerned to be an intercessor for those that ate the passover otherwise than it was written. And he had confidence that God was so gracious that he would not, on account of the omission of some prescribed ceremony, be wroth with men whose hearts were upright before him.