with a grain/pinch of salt, (to take)

with a grain/pinch of salt, (to take)

Not to be believed entirely; to be viewed with skepticism. This term comes from the Latin cum grano salis, which appeared in Pliny’s account of Pompey’s discovery of an antidote against poison that was to be taken with a grain of salt added (Naturalis Historia, ca. a.d. 77). The term was quickly adopted by English writers, among them John Trapp, whose Commentary on Revelations (1647) stated, “This is to be taken with a grain of salt.”
See also: grain, of, pinch