There came to Jesus scribes and Pharisees, which were of Jerusalem, saying, Why do thy disciples transgress the tradition of the elders? for they wash not their hands when they eat bread. But he answered and said unto them, Why do ye also transgress the commandment of God by your tradition? Matt. 15:1-3.
We have to congratulate the scribes and Pharisees on their persistence. No matter how far they have to travel to attack Jesus they will do it. It is unfortunate that they couldn't find a better purpose for their dedication.
The conflict between Jesus and the Jewish leaders recorded in Matthew 15 and Mark 7 centers outwardly around ceremonial defilement. But at a more profound level, it involves the very nature of religion and the depth of human sinfulness.
The Pharisaic party had a purpose: to question Jesus about why His disciples broke the tradition of the elders. Note, they were not accusing Him of doing so, but of teaching His disciples to disrespect the traditions. And in that accusation they were quite right.
According to Matthew's Gospel, the problem had to do with the washing of hands. Here it is important to note that the issue wasn't sanitation but ceremonial uncleanliness. In their genuine and sincere desire to honor God, the Pharisees had picked up on His instruction on priestly washing in the sanctuary (Ex. 30:17-21) and expanded the idea to everyday life. In addition, they multiplied the number of things causing defilement and ritualized the cleansing process. So important did ceremonial washing become to them that they eventually devoted an entire book of the Mishnah (the written version of the oral tradition) to it (called Yadaim, or "Hands"). The faithful were required to wash their hands in the prescribed manner, or their food, and by extension their whole person, would be unclean and unfit for worshipping God. Meanwhile, Jesus illustrated in Matthew 15:3-6 that some of their traditions led them to transgress the Ten Commandments, notably the one directed at loving and caring for their parents.
Here we have a case of the sin of devotion--a sin of religious people trying hard to be religious and manufacturing rules in the process. That is not a pharisaic disease, but is also found among Catholics, Baptists, and Adventists. It shows up in the angry deacon, the Inquisition, and those who blow up when someone does not eat as they think they should.