Someone asked this question because they saw a verse where Paul seems to contradict Jesus. (In that instance, Jesus said the law will not pass away, yet Paul wrote it was passing away.) Also, since Jesus is God and Paul was a mortal, it makes it easier to prefer one over the other when these kinds of issues arise.
We must remember that Jesus Himself chose Paul, so we should not count Paul out too quickly. Jesus spoke directly to Paul in a vision in Acts 9:1-6. Then Jesus called an unnamed servant to lay hands on him, telling him that Paul was “a chosen vessel to me” in Acts 9:10-17. Paul was then filled with the Holy Spirit.
Paul testified of being taught by Christ and that He is the source of his wisdom (Galatians 1:10-17). Paul acted as an ambassador of Christ (2 Cor. 5:20) and was careful to represent His perspective in all his words and conduct. (Oh, that we would do the same!)
Much of his writings were derived from the Old Testament, which was written under the inspiration of God. In the end, Paul’s epistles were entered into the biblical canon as also inspired by God. In other words, his words are given equal weight as those in the OT. All his words, as well as Christ’s, were of God, so whatever they wrote will be in agreement when correctly understood. This is because God, being the author of the Bible, doesn’t contradict himself. So if you find a contradiction between Jesus and Paul, you need to search deeper.