Torah Portion: Mishpatim
Do not extend your hand with the wicked to be a bribable witness (Shemos 23:1).
It is a negative commandment that we not accept the testimony of a sinner, and that we not act upon his testimony in any manner, as is written, Do not extend your hand with the wicked to be a bribable witness (Shemos 23:1).
The root of this mitzvah obvious, for anybody who does not care about himself and does not care about his bad deeds, will also not care about other people, so it is not fitting that we believe him about anything.
This mitzvah applies in all places and at all times to men who are fit to judge and accept testimony.