quien sabe
/kɪˌɛn ˈsɑːbeɪ/(also keen sabe, quién sabe, quien savvy)
exclamation
Originally and frequently in Spanish-speaking contexts: ‘Who knows?’, ‘who can tell?’.
Origin
Mid 19th century; earliest use found in Robert Fitzroy (1805–1865), hydrographer and meteorologist. From Spanish quién sabe who knows from quién (interrogative pronoun) who + sabe, third person singular present indicative of saber to know.