"His instructions were to not run" or "His instructions were not to run"?

Question

Which of these sentences is grammatically correct and why?

His instructions were to not run

His instructions were not to run.

Without the word 'run' the word 'to' would immediately follow 'to', like: "His instructions were to run." If we had to construct a negative out of this, should we say "were not to" or "were to not run".

What I think is that we should use the former ("were to not run") because "His instructions were to not run" makes it sound like someone instructed, specifically, to not run. The latter ("were not to run") is more like saying that someone did not instruct to run (but he did not instruct to not run, either).

Answer 1

It all depends on what the instruction actually was. Both sentences are correct, but subtly different.

Suppose that what he said was "don't run!" In that case, his instructions were to not run.

But suppose he instead said "walk!" In that case, his instructions were not to run.

Pedantry aside, the second sentence of the two just sounds better and is easier to understand.

Answer 2

Both sentences are grammatically correct. In the first, we're being told what his instructions were: not run. In the second sentence, we're being told what his instructions weren't. Consider these scenarios:

What was he told to do?
His instructions were to not run. (We explicitly told him to walk.)

versus

Was he told to run?
His instructions were not to run. (We didn't actually mention running or walking.)

Either works, depending on the situation.