When I was a boy and Mother suspected that my story had been slightly amplified, she would say, "Son, look me in the eye!"  She was convinced that if I could look her in the eye and tell her something, it was the truth!  In Numbers Five of your Old Testament, there is a passage which I've never fully understood; nonetheless, it was a provision to determine whether a wife was lying about being unfaithful to her husband.  A wife who had been so accused went to the tabernacle, and took a vow before the Lord saying that she had slept with no one but her husband.  Then she drank water which had some dust from the tabernacle floor in it.  If she was telling the truth, there was no harm. If she was lying, she was cursed with childlessness.