Matthew 12:34
King James Version
“O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.”
Context
31Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy the Ghost shall not be forgiven unto men.
32And whosoever speaketh a word against the Son of man, it shall be forgiven him: but whosoever speaketh against the Holy Ghost, it shall not be forgiven him, neither in this world, neither in the to come.
33Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is known by fruit.
34O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.
35A good man out of the good treasure of the heart bringeth forth good things: and an evil man out of the evil treasure bringeth forth evil things.
36But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment.
37For by thy words thou shalt be justified, and by thy words thou shalt be condemned.