Forever, O Lord, thy word is settled in heaven. (Psa 119:89)
Every word of God is pure: he is a shield unto them that put their trust in him. (Prov 30:5)
Sometimes, one will encounter these and similar verses to support the doctrine of Sola Scriptura. However, Protestant apologists who appeal to these passages confuse the categories of quality and sufficiency. Scripture has the quality of being inspired, and that is what Psa 119:89 and Prov 30:5 teaches; however, neither do these passages teach formal sufficiency, something which would be an impossibility anyway, as the entirety of the Bible was not written when those these texts were written (sola scriptura can only be operative when the totality of scripture is available [tota scriptura] according to Protestant theologians and apologists). Only by engaging in a common logical fallacy can one appeal to passages that speak highly of the quality of Scripture can one read formal sufficiency into such passages.
Furthermore, scholarly commentators on the Bible does not support such an eisegetical reading of such texts. For instance, R.B.Y. Scott in his Anchor Bible commentary rendered the verse as “Everything God says has stood the test! He is their shields who trust in them.” Commenting on this passage, he wrote:
The reply of the orthodox believer to the challenge of the skeptic: God’s self-revelation in his word is confirmed in the experience of the religious man. The language is pedestrian and sounds like a composite quotation from written scripture; cf. Prov xvii 30 CV; Deut iv 2; Job xiii 10, xxiv 25. (R.B.Y. Scott, Proverbs & Ecclesiastes [Anchor Bible; Garden City: Doubleday, 1965], 176-77)
