Where does the saying 'Que sera sera' come from?

Answer 1

A Spanish expression which means 'Whatever will be, will be". The song that popularized this expression was sung by Doris Day in Alfred Hitchcock's movie "The Man Who Knew Too Much"
Que sera, sera = whatever will be, will be

Answer 2

Alfred Hitchcock's 'The Man Who Knew Too Much' (1956).

Answer 3

From Doris Day's lips when crooning the song and translating its title as Whatever will be will be. The notorious Dutch-Hungarian iconoclast and novelist Jan Cremer wrote an ode to her.