Funny... However, if Jesus said “it is written”. He was necessarily referring to the Old Teatament, as it was the only Scripture at the time. In all seriousness, I don’t understand the logic of saying the bible is the be all and end all... When it never says that, nor did Jesus. He did however, pass on many things that were not recorded in the gospels.
When asked, Jesus quoted scripture. Not church councils. We also have the New Testament, which wasn’t written at the time of Jesus’ ministry.
What we never see is Jesus citing the authority of the Jewish councils or saying, “Trust the priests of Israel”! And since the New Testament had no priests other than Jesus, that may be significant. And that is the real rub - that much of Catholic theology is in contradiction to what is written.