There was no conflict between what Jesus taught and what Paul taught, but they did not teach the same thing. Jesus never said that salvation was by grace through faith, nor was Paul a teacher of the law. Jesus purpose was to reveal the Father and to show men that they were sinners.
The law will not produce righteousness, nor will it save.
"Therefore by the deeds of the law there shall no flesh be justified in his sight: FOR BY THE LAW IS THE KNOWLEDGE OF SIN" Romans 3:20.
Jesus taught the law to show us that we don't measure up to God's standards.
Paul said that righteousness and salvation come by faith in Christ and his Gospel and not by the works of the law.
"And be found in him, not having my own righteousness which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith" Philippians 3:9.
