Jesus never told anyone to stop being Jewish. The Last Supper was a Passover Seder. He was observant to the end.
I suppose that all depends on what, precisely, you mean by that. Jesus did not tell anyone to stop being Jewish--that would be as absurd and undoable (to a human) as telling the Irish to be Polish, or Swedes to be Mongols. In other words, it would require changing the past. However, if you mean that Jesus never said that OT laws were obsolete, you are wrong:
""Are you so dull?" he asked. "Don't you see that nothing that enters a man from the outside can make him 'unclean'? For it doesn't go into his heart but into his stomach, and then out of his body." (In saying this, Jesus declared all foods "clean.")" Mark 17:18-19 (Emphasis mine).