Difference between ～てなさい and ～なさい


I encountered this command while reading a piece of fiction:

休んでなさい

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?




I don't think this is so much the difference between the two but rather a
combination of the two. Here the て-form is used in the continuous sense,
休んでいる, and the なさい is simply applied to the end. In this case it is telling
the person to _continue_ to rest, instead of to rest from here on. A more
intuitive reading would be like "Just relax. Stay there." This type of
request/command comes up here and there in various Japanese phrases. For
instance いい子にしてろ (heard in a manga once) "don't act up" or commonly 待ってて "wait
there for me." It doesn't carry over to English easily, but once you get the
concept it comes quite intuitively.




I don't think this is so much the difference between the two but rather a
combination of the two. Here the て-form is used in the continuous sense,
休んでいる, and the なさい is simply applied to the end. In this case it is telling
the person to _continue_ to rest, instead of to rest from here on. A more
intuitive reading would be like "Just relax. Stay there." This type of
request/command comes up here and there in various Japanese phrases. For
instance いい子にしてろ (heard in a manga once) "don't act up" or commonly 待ってて "wait
there for me." It doesn't carry over to English easily, but once you get the
concept it comes quite intuitively.

