Matthew Henry Commentary 2 Kings 23:1-3

"And the king sent, and they gathered unto him all the elders of Judah and of Jerusalem. And the king went up to the house of Jehovah, and all the men of Judah and all the inhabitants of Jerusalem with him, and the priests, and the prophets, and all the people, both small and great: and he read in their ears all the words of the book of the covenant which was found in the house of Jehovah. And the king stood by the pillar, and made a covenant before Jehovah, to walk after Jehovah, and to keep his commandments, and his testimonies, and his statutes, with all [his] heart, and all [his] soul, to confirm the words of this covenant that were written in this book: and all the people stood to the covenant." — 2 Kings 23:1-3 (ASV)

Josiah had received a message from God that the ruin of Jerusalem could not be prevented, but that he himself would only deliver his own soul; yet he does his duty and leaves the outcome to God. He solemnly led the people to commit to abolishing idolatry and to serving God in righteousness and true holiness. Although most were formal or hypocritical in this, much public wickedness would nevertheless be prevented, and they remained accountable to God for their own conduct.