"I'll make him an offer he can't refuse."

The 'offer' being 'do as I say or I'll kill you'.

This is the best-known line from The Godfather book (1969) and film (1972), both written by Mario Puzo. In fact, it is one of the best-known lines in any film and ranks second only to 'Frankly, my dear, I don't give a damn' as the most celebrated quotation from an American film.