2 Kings 23:21 - Joseph Benson’s Commentary on the Old and New Testaments

The king commanded, saying, Keep the passover, &c. Having abolished false worship, he now endeavours to set up the true worship of the true God. Thus he differed greatly from Jehu, who, when he had destroyed the worship of Baal, took no heed to walk in the commandments and ordinances of God. Josiah considered that we must not only cease to do evil, but also learn to do well, and that the way to keep out all abominable customs is to keep up all instituted ordinances. He therefore commanded all the people to keep the passover, which was not only a memorial of their deliverance out of Egypt, but a token of their being dedicated to him who brought them out, and of their communion with him. As it is written in this book of the covenant This book which he had found, wherein is contained the covenant made between God and Israel, and the terms of it.