The Apostles might have felt concerned that the truth spoken by Jesus would lead to temptations among those it was meant to enlighten, or they could have been troubled by the implication that nothing entering a man's mouth could render him unclean. Consequently, they brought this information to Jesus in hopes of prompting an explanation regarding His earlier statement.
The remark made in verse 11 had led the Pharisees astray; they were so accustomed to the practice of washing their hands before meals for the sake of spiritual cleanliness that they perceived Christ's words as a challenge to the law of purification. Their offense also stemmed from Christ addressing the people directly, undermining their authority with His teachings. In response to the news about the Pharisees’ offense, Jesus described either the Pharisaic doctrine, which was a human invention rather than a divine command, thus needing to be dismantled, or rebuked the Pharisees themselves: though they were leaders and instructors of the community, they were not God’s true representatives, as they did not act in harmony with His will and thus lacked His special guidance.
Therefore, they were to be disregarded: this could mean refraining from following their erroneous teachings, which would lead to destruction alongside them, or it could indicate leaving them to their own devices. Subsequently, the Apostle Peter, speaking for all the disciples, requested clarification from the Lord regarding the enigmatic remarks on what defiles a person by entering the mouth versus what does not. The Lord then explained clearly that what enters the mouth refers to food, while what comes out of a person’s mouth symbolizes all evil thoughts, lusts, and intents, emanating from the heart. These ill intentions reveal the impurity of the human soul and its moral degradation, while food simply passes through the body without impacting the spirit.