Gill says the disciples came "full of concern." They had watched Jesus expose the Pharisees in public, and they saw that the leaders took it badly. Gill suggests the disciples seemed to wish Christ had not said it, and that "they might fear that both Christ, and they themselves, would feel the effects of their wrath and rage." Barnes explains why the Pharisees reacted so strongly: they were so zealous of their traditions "that they could not endure that their absurdities should be exposed." Gill adds that perhaps they told Him so "that he would take some prudential step that he might not fall into their hands."

Jesus did not take back what He said. He answered, "Every plant, which my heavenly Father hath not planted, shall be rooted up" (Matthew 15:13). Then He told the disciples, "Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch" (Matthew 15:14). Barnes explains "Let them alone" as "do not be troubled at their rage." Peter then asked Him to explain the saying itself (Matthew 15:15).

The word "offended" is skandalizō, from the word for a stumbling block. Thayer explains that in this verse it means to cause someone to feel displeasure or to make them indignant. The Pharisees were not hurt in feelings only; they were angered that their teaching had been publicly contradicted.

These Pharisees had come with the scribes "of Jerusalem" (Matthew 15:1), the center of religious authority. That helps explain why the disciples were worried about crossing them.

Jesus' answer shows how He weighs offense. Some teaching must be uprooted because God never planted it. Barnes says that doctrines of which the Father was not the author "must be rooted up, or corrected," and so "it was no wonder if they were indignant." Truth that comes from the Father does not need to be withdrawn because powerful people dislike it.

Matthew Henry adds that when someone is offended by "a plain, seasonable declaration of the truth," we should not be troubled by it. Jesus' concern was not for His own reputation but for people led by blind guides toward the ditch.