swear by

• Audio (General Australian):

  (file)

swear by (third-person singular simple present swears by, present participle swearing by, simple past swore by, past participle sworn by)

1. To invoke in an oath; to swear upon.
2. (idiomatic) To trust wholeheartedly.

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

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

• Awbreys, bewrays