Proverbs 24:2
"For their heart studieth destruction, and their lips talk of mischief."
Cross References (ranked by relevance)
Behold, he travaileth with iniquity, and hath conceived mischief, and brought forth falsehood.
His mouth is full of cursing and deceit and fraud: under his tongue is mischief and vanity.
Draw me not away with the wicked, and with the workers of iniquity, which speak peace to their neighbours, but mischief is in their hearts.
They conceive mischief, and bring forth vanity, and their belly prepareth deceit.
None calleth for justice, nor any pleadeth for truth: they trust in vanity, and speak lies; they conceive mischief, and bring forth iniquity.
And said, O full of all subtilty and all mischief, thou child of the devil, thou enemy of all righteousness, wilt thou not cease to pervert the right ways of the Lord?
And David knew that Saul secretly practised mischief against him; and he said to Abiathar the priest, Bring hither the ephod.
Frowardness is in his heart, he deviseth mischief continually; he soweth discord.
He deviseth mischief upon his bed; he setteth himself in a way that is not good; he abhorreth not evil.
Which imagine mischiefs in their heart; continually are they gathered together for war.
That they may do evil with both hands earnestly, the prince asketh, and the judge asketh for a reward; and the great man, he uttereth his mischievous desire: so they wrap it up.
He that deviseth to do evil shall be called a mischievous person.