Jesus is emphasizing the importance of what he is about to say. The implied information can be made explicit. AT: "Listen carefully to what I say so that you may understand its meaning" (See: [[rc://en/ta/man/translate/figs-explicit]])
# enters into the mouth ... comes out of the mouth
Jesus is contrasting what a person eats to what a person says. Jesus means that God is concerned with what a person says rather than what a person eats. (See: [[rc://en/ta/man/translate/figs-metonymy]])