How to change Laravel Validation message for max file size in MB instead of KB?

Laravel comes with this validation message that shows file size in kilobytes:

file' => 'The :attribute may not be greater than :max kilobytes.',

I want to customize it in a way that it shows megabytes instead of kilobytes. So for the user it would look like:

"The document may not be greater than 10 megabytes."

How can I do that?

via Chebli Mohamed