Romans 16:18

and avoid them; for such people serve not our Lord Jesus Christ, but their own belly; and by a soothing address and good words deceive the hearts of the innocent.

James 1:8

A double-minded man is inconstant in all his ways.

1 Thessalonians 2:5

For neither at any time used we flattering speech, as ye know, nor covetous pretence, 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.

General references

Bible References

Flattering

Romans 16:18
and avoid them; for such people serve not our Lord Jesus Christ, but their own belly; and by a soothing address and good words deceive the hearts of the innocent.
1 Thessalonians 2:5
For neither at any time used we flattering speech, as ye know, nor covetous pretence, God is witness:

General references

Acts 12:22
And the people gave a shout, saying, It is the voice of a god, and not of a man: