Proverbs 26:25
"When he speaketh fair, believe him not: for there are seven abominations in his heart."
Cross References (ranked by relevance)
For even thy brethren, and the house of thy father, even they have dealt treacherously with thee; yea, they have called a multitude after thee: believe them not, though they speak fair words unto thee.
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.
Then if any man shall say unto you, Lo, here is Christ, or there; believe it not.
They speak vanity every one with his neighbour: with flattering lips and with a double heart do they speak.
Trust ye not in a friend, put ye not confidence in a guide: keep the doors of thy mouth from her that lieth in thy bosom.