swear by

present singular third person swears by · participle present swearing by · past swore by · participle past sworn by

1. transitiveTo invoke in an oath; to swear upon.
2. idiomatictransitiveTo trust wholeheartedly.

   He swears by cream of tartar to make the meringues stiff.

   2 more examples

   I swear by my Petit Larousse when it comes to learning French.

   But while Switzerland might swear by it, elsewhere the practice has a dark history.

   2016 June 24, Atlas Obscura, “A Brief History of the Referendum: From 13th century Switzerland to Brexit”, in atlasobscura.com