Vayikra: Zohar HaKodesh: Mitzvah 120 – Concept 570
“If a person will sin; if he accepted a demand for an oath, and he is a witness – either he saw or he knew – if he does not testify, he shall bear his iniquity. (Leviticus 5:1) Anybody who knows evidence must testify in court. (Rambam, Hilchot Eidut – The Laws of Evidence)
The Zohar understands this verse as referring to the warnings issued by God to the soul, which descends into this deceitful world when entering man’s body.