Jeremiah 9:5
Ver. 5. And they will deceive everyone his neighbour,.... In conversation, with lying words; and in trade and commerce, by art and tricking:
and will not speak the truth; with respect to facts they report, or goods they sell:
they have taught their tongue to speak lies; and become so accustomed to lying that they cannot do otherwise; it is as it were natural to them:
and weary themselves to commit iniquity; spared no pains to come at it, nor any in it, and go on even to weariness; are more laborious and indefatigable in committing sin than good men are in doing good; which shows great folly and stupidity. The Targum is,
"they are become foolish, they have erred.''