Psalms 12:2

¹ Help, LORD; for the godly man ceaseth; for the faithful fail from among the children of men.

They speak vanity every one with his neighbour: with flattering lips and with a double heart do they speak.

³ The LORD shall cut off all flattering lips, and the tongue that speaketh proud things:

⁴ Who have said, With our tongue will we prevail; our lips are our own: who is lord over us?

Do read the surrounding verses too, because the context often says more than a single verse.

Compare

BSB: They lie to one another; they speak with flattering lips and a double heart.
KJV: They speak vanity every one with his neighbour: with flattering lips and with a double heart do they speak.
WEB: Everyone lies to his neighbor. They speak with flattering lips, and with a double heart.
ASV: They speak falsehood every one with his neighbor: With flattering lip, and with a double heart, do they speak.
DARBY: They speak falsehood every one with his neighbour: [with] flattering lip, with a double heart, do they speak.
BLB: Vanity they speak, each man with his neighbor; [with] lips of flattery with a double heart they speak.

ÅB: Hver enkelt lyver for sin neste;
de taler med falske lepper og med tvesinnet hjerte.
OTB: De taler svikefullt til hverandre;
de bruker smigrende lepper og har dobbelthet i hjertet.
B1930: Løgn taler de, hver med sin næste, med falske leber; med tvesinnet hjerte taler de.

Romans 16:18
For they that are such serve not our Lord Jesus Christ, but their own belly; and by good words and fair speeches deceive the hearts of the simple.
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Jeremiah 9:8
Their tongue is as an arrow shot out; it speaketh deceit: one speaketh peaceably to his neighbour with his mouth, but in heart he layeth his wait.
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Psalms 41:6
And if he come to see me, he speaketh vanity: his heart gathereth iniquity to itself; when he goeth abroad, he telleth it.
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Psalms 144:8
Whose mouth speaketh vanity, and their right hand is a right hand of falsehood.
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Psalms 10:7
His mouth is full of cursing and deceit and fraud: under his tongue is mischief and vanity.
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Psalms 5:9
For there is no faithfulness in their mouth; their inward part is very wickedness; their throat is an open sepulchre; they flatter with their tongue.
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Psalms 28:3
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.
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James 1:8
A double minded man is unstable in all his ways.
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