'Tradition of the Elders' in the Bible

Why do thy disciples transgress the tradition of the elders? for they wash not their hands when they eat bread.

For the Pharisees, and all the Jews, except they wash their hands oft, eat not, holding the tradition of the elders.

Then the Pharisees and scribes asked him, Why walk not thy disciples according to the tradition of the elders, but eat bread with unwashen hands?