"It is impossible that Scripture should contradict itself; it only appears so to senseless and obstinate hypocrites WA, 9,356.
"Everyone knows that at times they [the fathers] have erred as men will; therefore, I am ready to trust them only when they prove their opinions from Scripture, which has never erred." WA. 7, 315: cf. WA. 15. 1481"We see with what great diligence Moses, or rather the Holy Spirit, describes even the most insignificant acts and sufferings of the patriarchs." WA, 44, 91-92 (on Gen. 32:21-24).
"Who can think this through to his satisfaction? A man [Jonah] lives three days and three nights in solitude, without light, without food, in the midst of the sea, in a fish, and then comes back. I dare say that is what you would call a strange voyage. Indeed, who would believe it and not consider it a lie and a fable if it did not stand recorded in Scripture?" WA, 19, 219 (Exposition of Jonah) 1536fl
"He who carefully reads and studies the Scriptures will consider nothing so trifling that it does not at least contribute to the improvement of his life and morals, since the Holy Spirit wanted to have it committed to writing." WA. 42, 474 (on Gen. 12:11-13).
"The two incidents - that not a bone of the Lord Christ was broken and that His side was opened with a spear - do not appear to be of any particular significance. And yet, since the evangelist John adduces clear testimonies of Scripture, proving that Moses (Ex. 12:46) and Zechariah (12:10) predicted these things centuries before, we must confess that they are of great importance, no matter how insignificant the incidents seem to be; for the Holy Spirit does not speak anything to no purpose and in vain. " WA 4 52, 811 (on John 19:25-37).
"In the article of the [Nicene] Creed which treats of the Holy Spirit we say, ''Who spake by the prophets.' Thus we ascribe the entire Holy Scripture to the Holy Spirit." WA, 54, 35 (for Luther it was axiomatic that the Spirit could not err).
"Not only the words which the Holy Spirit and Scripture use are divine, but also the phrasing. WA, 40 III, 254 (on Ps. 127:3).
"The Holy Spirit is not a fool or a drunkard to express one point, not to say one word, in vain." WA, 40 III, 254 (on Ps. 127:3). WA, 54. 39 (discussion of Gen. 19:24 and I Chron. 17:10).
I've culled these quotes from John Warwick Montgomery's essay 'Lessons From Luther on the Inerrancy of Holy Writ'. Another valuable on-line resource readers might like to consult is J. M. Reu's 'Luther and the Scriptures'.
Modern scholars may not be able to believe in the inerrancy of scripture, but merely asserting that Luther shared their scepticism does not make it so. The theologians who, in the 17th century and later, explicated the teaching of Biblical inerrancy were closer to Luther than Oberman thought.