A six letter word to command not to do something is to forbid.
The word that means "to say something that is untrue" is "lie".
something that cannot be avoided = inevitable
A four letter word meaning the foundation of something is base.
obsession
A six letter word to command not to do something is to forbid.
The word is "command".
The root mandat- in the word mandatory means "command" or "order." It signifies something that is required or obligatory.
Forbid you
The Spanish word "repitan" translates to "repeat" in English. It is a command form of the verb "repetir," which means to say or do something again.
A single word would be 'order'.
Order
It is a command. It means "write".
The meaning of the word forbid is to not allow something or prevent something from happening. It can also be applied to stopping someone from doing something - as in forbidding a princess from leave a tower.
One possibility is the word law.
vice maybe
The subject "you" is rarely stated in a command, so "Please stop talking" would be the usual form. This means "You should please stop talking." (Perhaps the question is "what word is not necessary in this command?")