These are the basis of the Rabbinical writings that form the literature of present-day Judaism. The Pharisees' present-day descendents to be found among the Hassidim, what we refer to in America as the Orthodox branch of Judaism. The idea was that obedience to the tradition of the elders formed a barrier that would prevent a pious Jew from breaking a Biblical commandment itself. Here's an example, though it didn't seem to be an issue in Jesus' day, but much later. Plucking a handful of grain is harvesting.
Healing is the work a physician performs.
Fasting, on special occasions, as a sign of repentance. Jesus does not reprove them for this. All people are to wash hands before eating lest they pass ritual uncleanness to food, which, when eaten, would render the whole body unclean. The Pharisees had developed a deceptive method of swearing. Jesus' Criticism of the Pharisees Jesus faulted the Pharisees at two points in particular.