with a grain of salt

Calque of Latin cum grānō salis , literally with a grain of salt, figuratively with a bit of common sense (from Pliny’s Pompey’s discovery of an antidote against poison to be taken with a grain of salt).

• "I take anything I read on the Internet with a grain of salt."
• "In it, police laid out list of biographical factoids about BTK and urged residents to read it with a grain of salt. Releasing a list of his “claims,” they reasoned, might allow someone, somewhere to make a connection that police couldn't hope to."

• with all the salt in the Dead Sea