They had seen the disciples eat without first washing their hands, and they treated it as a religious offense. Mark says they saw the disciples eat "with defiled, that is to say, with unwashen, hands" and "found fault" (Mark 7:2). Notice the charge: the disciples had not broken a law of God but "the tradition of the elders." Barnes explains that this meant a custom "not commanded in the written law, but which scribes and Pharisees held themselves bound to observe." Gill observes that they "thought proper to take no notice of him as yet, but of them," aiming at the disciples first. Yet they put the question to Jesus Himself.

Jesus answered with a question of His own: "Why do ye also transgress the commandment of God by your tradition?" (Matthew 15:3). He showed how their tradition about gifts let a man escape the command to "Honour thy father and mother" (Matthew 15:4-6), and He applied Isaiah's words to them: "This people draweth nigh unto me with their mouth... but their heart is far from me" (Matthew 15:7-8). Then He called the crowd and taught that what defiles a man comes out of the mouth, not what goes in (Matthew 15:10-11). He closed the matter plainly to His disciples: "to eat with unwashen hands defileth not a man" (Matthew 15:20).

The word "tradition" is paradosis, something handed down. Thayer describes it as a body of precepts, especially ritual ones, that were passed on orally. Barnes explains the belief behind it: the Jews held that Moses received two sets of laws at Sinai, one written in the Old Testament and one handed down by word of mouth until it was later written in the Talmud (the collected body of Jewish oral law and its commentary).

Mark adds that "the Pharisees, and all the Jews, except they wash their hands oft, eat not," and that the washing extended to cups, pots, and brass vessels (Mark 7:3-4). Barnes notes that the washing was done professedly for cleanliness, "So far it was well," but it had become a matter of superstition, with rules about the amount of water and the manner of washing. Gill notes the rule applied to "common bread, an ordinary meal," not only to holy food.

The leaders asked about hands, and Jesus answered about hearts. Their question assumed that a person is made clean or unclean by outward rites. Jesus used it to show that God looks for a heart that is near to Him, not lips that honor Him while the heart is far away (Matthew 15:8, quoting Isaiah 29:13).

The question also shows how easily human rules can grow until they stand beside God's word as equals. Matthew Henry warns that "Additions to God's laws reflect upon his wisdom, as if he had left out something which was needed." The God of Scripture has already spoken clearly about what He requires, and Jesus held people to that.