The Ninth Commandment (9 of 10, God's Law) Thou shalt not bear false witness against thy neighbour (Exodus 20:16).

The original Westminster Larger Catechism (1648), on the ninth commandment, teaches,

Question 144: What are the duties required in the ninth commandment?
Answer: The duties required in the ninth commandment are, the preserving & promoting of truth between man and man, & the good name of our neighbor, as well as our own; appearing and standing for the truth; and from the heart, sincerely, freely, clearly, and fully, speaking the truth, and only the truth, in matters of judgment and justice, and in all other things: Whatsoever; a charitable esteem of our neighbors; loving, desiring, and rejoicing in their good name; sorrowing for, and covering of their infirmities; freely acknowledging of their gifts and graces, defending their innocency; a ready receiving of a good report, and unwillingness to admit of an evil report, concerning them; discouraging talebearers, flatterers, and slanderers; love and care of our own good name, and defending it when need requires; keeping of lawful promises; studying and practicing of: Whatsoever things are true, honest, lovely, and of good report.

Question 145: What are the sins forbidden in the ninth commandment?
Answer: See http://www.swrb.com/newslett/actualNLs/WLC.htm

And remember the Lord Jesus Christ said, 'If ye love me, keep my commandments.' (John 14:15)

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