613 Mitzvot
Negative Mitzvah 1
You shall not cover up for a "Maysit"
Lo-toveh lo velo tishma elav velo-tachos eynecha alav
velo-tachmol velo-techaseh
alav.
Do not agree with him, and do not listen to him. Do not
let your eyes pity him, do not show him any mercy, and do not try to
cover up for him
The purpose here again is to prevent hindrances to the justice of YHVH. The matter of the person misleading to idols must be investigated.
Deuteronomy 13:14 then shall you inquire, and make search, and ask diligently; and, behold, if it be truth, and the thing certain, that such abomination is done in the midst of you"
This is established by two or three witnesses.
One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sins: at the mouth of two witnesses, or at the mouth of three witnesses, shall a matter be established. If an unrighteous witness rise up against any man to testify against him of wrong-doing, then both the men, between whom the controversy is, shall stand before YHVH, before the kohanim and the judges who shall be in those days; and the judges shall make diligent inquisition: and, behold, if the witness is a false witness, and has testified falsely against his brother; (Deuteronomy 19:15-18)
We should not cover up for the misleader by hiding evidence against him. If we hid evidence, this would be the same as testifying falsely? So this is also a matter of truthfulness as well.