2 Chronicles 34:21
Go, enquire of the LORD for me, and for them that are left in Israel and in Judah, concerning the words of the book that is found: for great is the wrath of the LORD that is poured out upon us, because our fathers have not kept the word of the LORD, to do after all that is written in this book.
The book of the law, which had been lost and neglected, was found in the house of the Lord in Josiah's time and read before the king. On hearing it he tore his garments and grieved over the people's failure to keep the law, humbling his heart and weeping before the Lord. He then commanded men in holy office to inquire of the Lord for himself and for those left in Israel and in Judah.
He did so because their fathers had not kept the word of the Lord to do all that was written in the book, but had departed from His statutes, leaving them exposed to great wrath poured out upon them. Hearing the book exposes disobedience and brings mourning under its warning and condemnation for trampling Heaven's precepts, yet discovering the fault gives reason to turn back, obey God's commandments, and live. That turning means confessing transgression and entering a solemn covenant to keep the statutes and commandments with the whole heart.
It then means gathering all Israel to hear the words of the book, pointing out the sin of rulers and people, manifesting repentance, making thorough reformation, and not resting until the people have done all they can to return from backsliding and serve the living God, which God accepted. The verse illustrates the deep repentance and return to the Lord that John's preaching expected. The same work is required today, for God has opened the book of the law so backslidden Israel hears the commandments with transgression revealed, and His wrath will be upon every soul who does not repent and reform as light shines on his pathway.
Therefore all must repent of past evil doings, seek God with all the heart, believe God means just what He says, make no compromise with evil, humble themselves greatly before God, and count any loss preferable to the loss of His favor.