Matthew 12:34-35
You children of snakes! Since you are evil, how do you expect to speak good things? For the mouth speaks what the heart is filled with.
Luke 6:45
The good person produces good things from the goodness stored up in his heart. And the evil person produces bad things from the evil [stored up in his heart]. For his mouth speaks what his heart is filled with.
Matthew 15:19
For evil thoughts, murder, extramarital affairs, sexual immorality, stealing, perjury, slander --- [all these] come from a person's heart,
Mark 7:21-23
For from within, out of people's hearts, proceed evil thoughts, sexual immorality, stealing, murder, extramarital affairs,
Mark 14:38
Be alert and pray, so that you do not give in to temptation. The spirit of a person is truly willing [i.e., to do a certain thing], but his physical nature is [often] too weak [to carry it out]."
Hebrews 12:15
Look carefully [at how you are living] so that no one falls away from God's unearned favor, and that no "poisonous plant sprouts up" to cause trouble and corrupt many people [Note: This is an analogy from Deut. 29:16-18 being used as a warning against the evil influence of wicked people],
James 1:14-15
But each person is tempted when he is lured and enticed by his own evil desire.