“And when he was entered into the house from the people, his disciples asked him concerning the parable.”
King James Version (KJV)
7:15 There is nothing entering into a man from without which can defile him - Though it is very true, a man may bring guilt, which is moral defilement, upon himself by eating what hurts his health, or by excess either in meat or drink yet even here the pollution arises from the wickedness of the heart, and is just proportionable to it. And this is all that our Lord asserts.
7:19 Purging all meats - Probably the seat was usually placed over running water.