take someone's name in vain

take someone's name in vain

Speak casually or idly of someone, as in There he goes, taking my name in vain again. This idiom originated as a translation from the Latin of the Vulgate Bible (Exodus 20:7), "to take God's name in vain," and for a time was used only to denote blasphemy and profanity. In the early 1700s it began to be used more loosely as well.
See also: name, take, vain