Sometimes one will hear the claim that the reforms of Kings Hezekiah and Josiah support the formal sufficiency of Scripture (á la the doctrine of Sola Scriptura). However, in reality, both these kings relied on non-inscripturated revelation as a key source for many of their teachings. Consider the following texts:
And he [King Hezekiah] set the Levites in the house of the Lord with cymbals, with psalteries, and with harps, according to the commandment of David, and of Gad the king's seer, and Nathan the prophet: for so was the commandment of the Lord by his prophets. (2 Chron 29:25)
And prepare yourselves by the houses of your fathers, after your courses, according to the writing of David king of Israel, and according to the writing of Solomon his son. (2 Chron 35:4)
With respect to the first text, we learn the following: (1) firstly, David, Gad, and Nathan were dead for about 250 years at this point; however, (2) they passed on a "command . . . from the Lord" which was prescribed by God's prophets on how worship to be conducted in the temple (hardly a minor issue; the worship of God is a central issue in theology) and (3) such a prescription and commandment is nowhere found in the entirety of the Bible.
So instead of viewing scripture as being formally sufficient, Hezekiah and Josiah relied upon other sources than only inscripturated revelation in their reforms. Indeed, in no case did the believing community rebuke Hezekiah or Josiah for violating sola scriptura. On the contrary, they accepted the fact that divine instruction, through the mouths of God's prophets, had been preserved for the community's use for hundreds of years apart from inscripturated revelation. Indeed, Josiah relied upon the words of the prophetess Huldah, not just the Scriptures, including the text of Deuteronomy that was rediscovered (cf. 2 Kgs 22-24). As we read in 2 Chron 34:22-28:
And Hilkiah, and they that the king had appointed, went to Huldah the prophetess, the wife of Shallum the son of Tikvath, the son of Hasrah, keeper of the wardrobe; (now she dwelt in Jerusalem in the college:) and they spake to her to that effect. And she answered them, Thus saith the LORD God of Israel, Tell ye the man that sent you to me, Thus saith the Lord, Behold, I will bring evil upon this place, and upon the inhabitants thereof, even all the curses that are written in the book which they have read before the king of Judah: Because they have forsaken me, and have burned incense unto other gods, that they might provoke me to anger with all the works of their hands; therefore my wrath shall be poured out upon this place, and shall not be quenched. And as for the king of Judah, who sent you to enquire of the Lord, so shall ye say unto him, Thus saith the Lord God of Israel concerning the words which thou hast heard; Because thine heart was tender, and thou didst humble thyself before God, when thou heardest his words against this place, and against the inhabitants thereof, and humbledst thyself before me, and didst rend thy clothes, and weep before me; I have even heard thee also, saith the Lord. Behold, I will gather thee to thy fathers, and thou shalt be gathered to thy grave in peace, neither shall thine eyes see all the evil that I will bring upon this place, and upon the inhabitants of the same. So they brought the king word again.
It is rather obvious that the reforms one reads about in the Old Testament were not based on any concept of Sola Scriptura, the claims of some Protestant apologists notwithstanding.
