"To this vast assembly the king himself read “all the words of the book of the covenant which was found in the house of the Lord.” 2 Kings 23:2 . The royal reader was deeply affected, and he delivered his message with the pathos of a broken heart. His hearers were profoundly moved. The intensity of feeling revealed in the countenance of the king, the solemnity of the message itself, the warning of judgments impending—all these had their effect, and many determined to join with the king in seeking forgiveness. PK 400.2"
"And the king went up into the house of the Lord, 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 the Lord."
Ellen White directly references 2 Kings 23:2 in this passage.
"Josiah now proposed that those highest in authority unite with the people in solemnly covenanting before God to co-operate with one another in an effort to institute decided changes. “The king stood by a pillar, and made a covenant before the Lord, to walk after the Lord, and to keep His commandments and His testimonies and His statutes with all their heart and all their soul, to perform the words of this covenant that were written in this book.” The response was more hearty than the king had dared hope for: “All the people stood to the covenant.” Verse 3 . PK 400.3"
"And the king stood by a pillar, and made a covenant before the Lord, to walk after the Lord, and to keep his commandments and his testimonies and his statutes with all their heart and all their soul, to perform the words of this covenant that were written in this book. And all the people stood to the covenant."
EGW directly quotes 2 Kings 23:3.