Is this line from "Stalker" an allusion to Shakespeare?

Question

In Tarkovsky's Stalker one character states:

Well done, citizen Shakespeare. It’s frightening to go forward; it’s a shame to go back.

This further reminded me of the passage from Hart Crane's Southern Cross:

It is blood to remember; it is fire To stammer back

The translator of the Russian film however might not know the exact Shakespeare quote so might not have translated it to match the Shakespeare quote. Does anyone know what the exact allusion to Shakespeare is? If it is an allusion. For more context the character does on to state:

Therefore, you commanded yourself in a strange voice. You even became sober out of fear.

Doing the obvious Google searches does not yield any answers.

Answer 1

TL;DR: No.

The line from Stalker comes from the English dub of the film. Here’s a bit more context, starting at 19:50 in this YouTube video. Three men, Stalker, Professor and Writer, are approaching an apparently abandoned building in the Zone.

Writer goes slowly towards the building.

VOICE (off screen): Stop! Don’t move!

A cobweb or a translucent cloth falls down at the entrance of the building. Stalker and Professor look towards the building.

STALKER: Why did you?

PROFESSOR: What?

STALKER: Why did you stop him?

PROFESSOR: What? I thought it was you.

Writer stands still for a moment, then hurries back.

WRITER: What happened? Why did you stop me?

STALKER: I didn’t stop you.

WRITER (to Professor): You? (Professor shakes his head.) Damn it!

PROFESSOR: Well done, citizen Shakespeare. It’s frightening to go forward; it’s a shame to go back. Therefore, you commanded yourself in a strange voice. You even became sober out of fear.

In context, Professor is not quoting from Shakespeare, but rather using “citizen Shakespeare” as an ironic or mocking form of address for Writer, who, as the film makes clear early on, is no Shakespeare, but rather a drunk who has lost his inspiration and hopes to get it back in the Zone. When Professor says, “It’s frightening to go forward; it’s a shame to go back,” this is a literal description of the events that just took place.