Jeremiah 9:5

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.''