Psalm 12:2

Each one speaks vanity with his neighbour: they speak with flattering lips and with a double heart.

Psalm 41:6

And if he came to see me, he spoke lies: his heart gathered iniquity to itself, and when he goes out, he tells it.

Romans 16:18

For they that are such do not serve our Lord Jesus Christ, but their own belly and by smooth words and blessings deceive the hearts of the simple.

Psalm 10:7

His mouth is full of cursing and deceit and fraud: under his tongue is mischief and vanity.

Jeremiah 9:8

Their tongue is as a sharp arrow; it speaks deceit: one speaks peaceably to his neighbour with his mouth but in heart he lays in wait.

1 Chronicles 12:33

Of Zebulun, such as went forth to battle, expert in war, with all weapons of war, fifty thousand, who could keep rank; they were not of double heart.

Psalm 5:9

For there is no uprightness in their mouth; their inward part is very wickedness; their throat is an open sepulchre; they flatter with their tongue.

Psalm 28:3

Do not catch me away with the wicked, and with the workers of iniquity, who speak peace to their neighbours, but evil is in their hearts.

Psalm 144:8

whose mouth speaks vanity, and their right hand is a right hand of falsehood.

James 1:8

The double minded man is unstable in all his ways.

Psalm 36:3-4

The words of his mouth are iniquity and deceit; he has left off to be wise and to do good.

Psalm 38:12

Those that seek after my life lay snares for me, and those that seek my hurt speak calamities and imagine deceits all the day long.

Psalm 52:1-4

Why dost thou boast of evil, O strong man? The mercy of God is day by day.

Psalm 55:21

The words of his mouth were smoother than butter, but war was in his heart; his words were softer than oil, yet they were drawn swords.

Psalm 59:12

For the sin of their mouth and the words of their lips, let them even be taken in their pride; they shall be subject to weakness and to a curse.

Psalm 62:4

They only consult to cast him down from his greatness; they delight in lies; they bless with their mouth, but they curse in their inward parts. Selah.

Psalm 144:11

Redeem me, and save me from the hand of strange sons, whose mouth speaks vanity, and their right hand is a right hand of falsehood:

Proverbs 20:19

He that goes about as a talebearer reveals secrets; therefore meddle not with him that flatters with his lips.

Proverbs 29:5

The man that flatters his neighbour spreads a net for his feet.

Jeremiah 9:2-6

Oh that I had in the wilderness a lodging place of wayfaring men that I might leave my people and go from them! for they are all adulterers, a congregation of rebels.

Ezekiel 12:24

For there shall no longer be any vain vision or flattering divination within the house of Israel.

1 Thessalonians 2:5

For we were never flatterers in the word, as ye know, nor tainted with covetousness, God is witness,

Treasury of Scripture Knowledge

Summary

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

A double heart

Bible References

Flattering

Psalm 5:9
For there is no uprightness in their mouth; their inward part is very wickedness; their throat is an open sepulchre; they flatter with their tongue.
Psalm 28:3
Do not catch me away with the wicked, and with the workers of iniquity, who speak peace to their neighbours, but evil is in their hearts.
Psalm 62:4
They only consult to cast him down from his greatness; they delight in lies; they bless with their mouth, but they curse in their inward parts. Selah.
Proverbs 20:19
He that goes about as a talebearer reveals secrets; therefore meddle not with him that flatters with his lips.
Proverbs 29:5
The man that flatters his neighbour spreads a net for his feet.
Ezekiel 12:24
For there shall no longer be any vain vision or flattering divination within the house of Israel.
Romans 16:18
For they that are such do not serve our Lord Jesus Christ, but their own belly and by smooth words and blessings deceive the hearts of the simple.
1 Thessalonians 2:5
For we were never flatterers in the word, as ye know, nor tainted with covetousness, God is witness,

A double heart

1 Chronicles 12:33
Of Zebulun, such as went forth to battle, expert in war, with all weapons of war, fifty thousand, who could keep rank; they were not of double heart.

General references

Genesis 29:19
And Laban said, It is better that I give her to thee than that I should give her to another man; abide with me.
Judges 16:6
And Delilah said to Samson, Tell me, I pray thee, what gives thee thy great strength and how might thou be bound to afflict thee.
Habakkuk 1:3
Why dost thou cause me to see iniquity and cause me to behold grievance and destruction and violence before me, in addition to those that raise up strife and contention?
Acts 12:22
And the people gave a shout, saying, It is the voice of god, and not of man.