In the Gospel of John, Jesus is recorded as referring to scripture as being fixed, presumably because it comes from God:
John 10:35
"If he called them gods, unto whom the word of God came, and the scripture cannot be broken..."
God speaking through the mouth of David:
Acts 4:24-25:
"...Lord, thou art God, which hast made heaven, and earth, and the sea, and all that in them is: Who by the mouth of thy servant David hast said, Why did the heathen rage, and the people imagine vain things?"
Inspiration of the Holy Spirit
1 Corinthians 2:9-13:
"But as it is written, Eye hath not seen, nor ear heard, neither have entered into the heart of man, the things which God hath prepared for them that love him. But God hath revealed them unto us by his Spirit: ...Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God. Which things also we speak, not in the words which man's wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual."
The "word of God," not of men:
1 Thesalonians 2:13:
"For this cause also thank we God without ceasing, because, when ye received the word of God which ye heard of us, ye received it not as the word of men, but as it is in truth, the word of God, which effectually worketh also in you that believe."
2 Timothy 3:16:
"All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness."
2 Peter 1:20-21:
"Knowing this first, that no prophecy of the scripture is of any private interpretation. For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.
Brimshack, the premise is that all the scriptures are God breathed, whether Christ actually spoke them, or if men wrote as if they were moved by the holy spirit.