How to Say "don't sign" in Spanish
The Spanish word for “don't sign” is “firmes” — B1 level.

Examples
Te pido que firmes este documento inmediatamente.
I ask that you sign this document immediately. (This uses the special form 'firmes' because it expresses a request.)
No firmes nada si no entiendes todas las cláusulas.
Don't sign anything if you don't understand all the clauses. (This is a direct, negative command.)
Es crucial que firmes antes de que termine el día.
It is crucial that you sign before the day ends.
The Special 'Wish' Form (Subjunctive)
The form 'firmes' (tú) is used when the sentence expresses doubt, emotion, wish, or necessity. For example, 'Dudo que firmes a tiempo' (I doubt you will sign in time).
Negative Commands
When you tell someone (tú) not to do something, you use the subjunctive form, which is 'No firmes.' This is different from the affirmative command ('Firma!').
Mixing Command Forms
Mistake: “Using 'No firmas' when giving a negative command.”
Correction: Always use the special form for negative commands: 'No firmes.' (Don't sign).
Related Translations
Learn Spanish with Inklingo
Interactive stories, personalized learning, and more.