Part — Slater, Manual of Moral Theology
Part VIII. The Eighth Commandment
1.
The Eighth Commandment of the Decalogue is, “ Thou shalt not bear false witness against thy neighbour.”1 Primarily it forbids the giving of false evidence, especially in a court of justice, against one’s neighbour, by which his reputation is unjustly injured. But because the same effect is produced by rash judgements, calumny, tale-bearing, backbiting, contumely, lying, and the betrayal of secrets, all these sins are also forbidden by this commandment. Inasmuch as it is virtually positive, it prescribes the telling of the truth.
1 Exod. xx. 16.
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