Psalm 12:2

They speak falseness {to each other}. [With] flattering lips, [with] {a double heart} they speak.

Psalm 41:6

And when one comes to see [me], he speaks falsely; his heart gathers disaster for itself. He goes out to the street; he speaks.

Romans 16:18

For such people do not serve our Lord Christ, but their own stomach, and by smooth speech and flattery they deceive the hearts of the unsuspecting.

Psalm 10:7

His mouth is filled with cursing, with deceits and oppression; under his tongue are trouble and evil.

Jeremiah 9:8

Their tongue [is] a murderous arrow, it speaks deceit. With his mouth he speaks peace with his neighbor, but in his inner parts he sets up his ambush.

1 Chronicles 12:33

From Zebulun, those who went out armed, equipped for battle with all the weapons of war: fifty thousand to help David {with singleness of purpose}.

Psalm 5:9

For there is not [anything] reliable in his mouth; their inner part [is] destruction. Their throat is an open grave; [with] their tongue they speak deceit.

Psalm 28:3

Do not drag me away with [the] wicked or with [the] workers of evil, [who] speak of peace with their neighbors, while evil [is] in their heart.

Psalm 144:8

whose mouth speaks falsely, and their right hand [is] a false right hand.

James 1:8

[he is] a double-minded man, unstable in all his ways.

Psalm 36:3-4

The words of his mouth [are] wickedness and deceit. He has ceased to have insight [and] to do good.

Psalm 38:12

Those who seek my life lay snares as well, and those intent on my harm speak threats. They also plot deceit all day.

Psalm 52:1-4

Why do you boast about evil, O mighty man? The loyal love of God [endures] {continually}.

Psalm 55:21

The {buttery words} of his mouth were smooth, but [there was] battle in his heart. His words were smoother than oil, but they [were] drawn swords.

Psalm 59:12

[By] the sin of their mouth [and] the words of their lips, even in their pride, let them be trapped, and for [the] curses and lies they proclaim.

Psalm 62:4

They only plan to thrust [him] down from his high position; they are pleased [with] deception. With their mouths they bless, but {inwardly} they curse. Selah

Psalm 144:11

Rescue me and deliver me from [the] hand of foreigners, whose mouth speaks falsely, and whose right hand [is] a false right hand,

Proverbs 20:19

He reveals a secret, he who walks [about with] gossip, and do not associate with a babbler's lips.

Proverbs 29:5

A strong man who flatters his neighbor is spreading a net for his feet.

Jeremiah 9:2-6

{Oh that I had} in the desert a place of overnight lodging for travelers, that I may leave my people and go from them, for all of them [are] adulterers, a band of traitors.

Ezekiel 12:24

For [there] will not be any longer {any false vision} or flattering divination in the midst of the house of Israel.

1 Thessalonians 2:5

{For never} did we come with a word of flattery, just as you know, nor with a pretext of greediness (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 not [anything] reliable in his mouth; their inner part [is] destruction. Their throat is an open grave; [with] their tongue they speak deceit.
Psalm 28:3
Do not drag me away with [the] wicked or with [the] workers of evil, [who] speak of peace with their neighbors, while evil [is] in their heart.
Psalm 62:4
They only plan to thrust [him] down from his high position; they are pleased [with] deception. With their mouths they bless, but {inwardly} they curse. Selah
Proverbs 20:19
He reveals a secret, he who walks [about with] gossip, and do not associate with a babbler's lips.
Proverbs 29:5
A strong man who flatters his neighbor is spreading a net for his feet.
Ezekiel 12:24
For [there] will not be any longer {any false vision} or flattering divination in the midst of the house of Israel.
Romans 16:18
For such people do not serve our Lord Christ, but their own stomach, and by smooth speech and flattery they deceive the hearts of the unsuspecting.
1 Thessalonians 2:5
{For never} did we come with a word of flattery, just as you know, nor with a pretext of greediness (God [is] witness),

A double heart

1 Chronicles 12:33
From Zebulun, those who went out armed, equipped for battle with all the weapons of war: fifty thousand to help David {with singleness of purpose}.

General references

Genesis 29:19
Then Laban said, "Better [that] I give her to you than I give her to another man. Stay with me."
Judges 16:6
So Delilah said to Samson, "Please tell me what makes your strength so great, and with what can you be tied up to subdue you?"
Habakkuk 1:3
Why do you cause me to see evil [while] you look at trouble? Destruction and violence happen before me; contention and strife arise.
Acts 12:22
But the people began to call out loudly, "The voice of a god and not of a man!"