And of course further on down in chapter 15 where Jesus actually explained what He meant He stated this...
16 “Are you still so dull?” Jesus asked them. 17 “Don’t you see that whatever enters the mouth goes into the stomach and then out of the body? 18 But the things that come out of the mouth come from the heart, and these make a man ‘unclean.’ 19 For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false testimony, slander. 20 These are what make a man ‘unclean’; but eating with unwashed hands does not make him ‘unclean.’”