The term PLENARY INSPIRATION involves the belief that every and all parts of the Bible are equally inspired and equally authoritative.
Romans 15:4 says:
For whatsoever things were written aforetime were written for our learning, that we through patience and comfort of the scriptures might have hope.
Notice, the things written AFORETIME in the Old Testament, are authoritatively called the SCRIPTURES. And Jesus said in the New Testament that "the scripture cannot be broken."
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: