The structure of Mark 3:1-6 seems to be basically chiastic:

A. Jesus’ entry to synagogue

B. man with withered hand

C. heal on Sabbath?

D. Jesus to man

E. Jesus to Pharisees

F. Silence

E’. Jesus angry and grieved at Pharisees

D’. Jesus to man

C’. ??

B’. restored hand

A’. Pharisees consult with Herodians about how to destroy him

Two observations: First, the Pharisees’ silence seem to be central, the turning point of the story and one of a series of important turning points in the gospel. Jesus reacts to their silence with the beginnings of eschatological wrath and grief. Second, the fact that the text doesn’t return to the Sabbath issue is noteworthy. The Pharisees are very interested in learning whether Jesus will break the Sabbath, but by the end of the story their Sabbatarianism is just dropped, as they go out to plot a murder. As they forget the Sabbath, Mark leaves an open space in the story where we would expect another Sabbath reference.