Q.83: What is forbidden in the ninth commandment?
A. The ninth commandment forbids whatsoever is prejudicial to truth, or injurious to our own or our neighbor’s good name.
LORD, who may abide in Your tabernacle? Who may dwell in Your holy hill? …He who does not backbite with his tongue, Nor does evil to his neighbor, Nor does he take up a reproach against his friend. Psalm 15:1,3