Matthew 15:2

The tradition of the elders (thn paradosin twn presbuterwn). This was the oral law, handed down by the elders of the past in ex cathedra fashion and later codified in the Mishna. Handwashing before meals is not a requirement of the Old Testament. It is, we know, a good thing for sanitary reasons, but the rabbis made it a mark of righteousness for others at any rate. This item was magnified at great length in the oral teaching. The washing (niptontai, middle voice, note) of the hands called for minute regulations. It was commanded to wash the hands before meals, it was one's duty to do it after eating. The more rigorous did it between the courses. The hands must be immersed. Then the water itself must be "clean" and the cups or pots used must be ceremonially "clean." Vessels were kept full of clean water ready for use ( John 2:6-8 ). So it went on ad infinitum. Thus a real issue is raised between Jesus and the rabbis. It was far more than a point of etiquette or of hygienics. The rabbis held it to be a mortal sin. The incident may have happened in a Pharisee's house.