פירוש על מכות 3:7

One who profanes (others) does not himself become profane - A priest who marries a divorcee, that disqualifies his offspring, he himself does not become disqualified:

One who comes to disqualify and does not (successfully) disqualify - A false witness that wants to disqualify and does not (successfuly) disqualify, how much more so etc. (alt. is it not logical etc.):

If so - If you come to expound this a fortiori inference with false witnesses, you will have nullified (the application of) the law of false witnesses: