Matthew 15:15 - Ellicott's Commentary On The Whole Bible

Declare unto us this parable. — The answer shows that Peter’s question referred not to the proverb that immediately preceded, but to what seemed to him the strange, startling utterance of Matthew 15:11. It was significant that he could not as yet take in the thought that it was a truth to be received literally. To him it seemed a dark enigmatic saying, which required an explanation, like that which had been given of the parable of the Sower, to make its meaning clear.