"If anyone sins because they do not speak up when they hear a public charge to testify regarding something they have seen or learned about, they will be held responsible." (NIV)
IF ANYONE sins in that he is sworn to testify and has knowledge of the matter, either by seeing or hearing of it, but fails to report it, then he shall bear his iniquity and willfulness. (AMP)
And if a soul sin, and hear the voice of swearing, and is a witness, whether he hath seen or known of it; if he do not utter it, then he shall bear his iniquity. (KJV)