Torah Portion: Yisro
Do not testify as a false witness against your neighbor (Shemos 20:13).
It is forbidden by negative commandment to give false testimony, as it says, Do not testify as a false witness against your neighbor (Shemos 20:13).
The root reason for this commandment is apparent: falsehood is vile and loathsome to every intelligent person. Also, it is through true testimony that the world endures because when there is true testimony all matters of dispute between people are resolved; if, instead, there is false testimony it is a cause of ruin for civilization.
This commandment applies in all places, to men who are fit to act as witnesses. One who transgresses this commandment and testifies falsely against his fellow, is punished by having done to him what he schemed would be done to his fellow, [the victim].