Matthew 26:31-35 Then Jesus told them, "This very night you will all fall away on account of me, for it is written: "'I will strike the shepherd, and the sheep of the flock will be scattered.' (32) But after I have risen, I will go ahead of you into Galilee." (33) Peter replied, "Even if all fall away on account of you, I never will." (34) "I tell you the truth," Jesus answered, "this very night, before the rooster crows, you will disown me three times." (35) But Peter declared, "Even if I have to die with you, I will never disown you." And all the other disciples said the same.
Many times we comfort ourselves and say, "I'm glad that I never did that." However, we deny Jesus every time that we do not open our mouths. We deny him with our silence.