Yeshua (Jesus) answered them, "You go astray because you are ignorant of both the Tanakh and the power of God. (Matthew 22:29)
The "Tanakh" is what we call the "Old Testament". Anytime the "New Testament" writers refer to the "Scriptures", they are referring to the Tanakh. Remember, they did not have the New Testament when they said and wrote those things. What we know as the New Testament canon did not form until 364AD at the Council of Laodicea.
Yeshua said that we go astray (error, make mistakes, fail, misunderstand, etc) because we do not know the Tanakh (Matt 22:29). We make errors because we do not understand the "Old Testament". We fail because we have failed to learn the Scriptures. Wow. We could stop right there and just meditate on that for a while.