Did Jesus teach a gospel of Salvation by works? Most people would say no. This is true he did not,  he taught faith and repentance. So why did he say this?

Matthew 13:41 "The Son of Man will send his angels, and they will gather from his kingdom everything that causes sin as well as all lawbreakers. ⁴² They will throw them into the fiery furnace, where there will be weeping and gnashing of teeth."NET