I encountered this command while reading a piece of fiction:
I learned that the pre-masu form is used with imperatives using なさい. So, I would have expected 休みなさい. But, here, the て form is used.
Why is the -te form used here? Is there a difference in meaning or nuance between the -te form and pre-masu form when used with なさい? Is this usage a specific and irregular form used only with the verb 休む, perhaps due to the already pre-existing fixed expression おやすみなさい?