The negative tú command of the verb dar is no des.
In Spanish, commands (or imperatives) can be formed in different ways depending on whether we want to give a positive or negative instruction. For the negative tú command, we typically use the present subjunctive form of the verb.
In the case of the verb dar (to give), its conjugation in the present subjunctive for the tú form is des. To make it negative, we simply add no in front of it. Therefore, the phrase you would use to tell someone not to give something is no des.
For example: No des esos libros a nadie. (Don’t give those books to anyone.)