[General] don't permit you to cast aspersions

[Silverobama]

Hi.

I think "I don't permit you to cast aspersions on my friend" is natural and formal. If it's not, please tell me. I wonder if the colloquial way to express the same idea would be "I don't think you should say bad things on my friend". (If both are not natural, please tell me the natural way to say so.)

 

[tedmc]

"To cast aspersions" is a legal jargon commonly used in defamation suits. It is not used in normal writing.

"I don't think you should say bad things [STRIKE]on[/STRIKE] about my friend".

The above is okay.
I would say, "Dont bad-mouth/vilify my friend".

 

[Silverobama]

No. You may object to somebody casting aspersions or tell them not to, but "I don't permit you to cast aspersions" is not natural.

May I ask for an alternative?

 

[GoesStation]

May I ask for an alternative?

With Ted's correction, the version you described as "colloquial" is fine.