I saw the movie "Love Hard" yesterday. In the film, the little brother hates his big brother.
The little brother is at home and suddenly he hears his big brother's voice when the big brother visits him.
The little brother says "Speak of the devil"
The dictionary just says
(informal) people say speak/talk of the devil when somebody they have been talking about appears unexpectedly
Well, speak of the devil—here's Alice now!
It did not say whether the speaker hates the arriver or not.
I really respect my grandma, and when my grandma suddenly visits my house.
Is it rude to say "Speak of the devil- Here is Grandma now!"?