What is the meaning of "Ed Beliya'al Yalitz Mishpat"?
Rashi: It will testify to a man a metaphor of judgments of afflictions and death.
R. Yonah: He will claim and prosecute liability. This is like "Im Yesh Alav Mal'ach Melitz" (Iyov 33:23), "Yalitz Asham" (above, 14:9). One who always prosecutes liability on people, and judges them unfavorably, from this Midah he will come to testify falsely. He will detract from or add to what he will see, for he desires to condemn his colleague.
Malbim: A false witness mocks Mishpat. Via him, there is Mishpat to kill unlike the law, like the episode with Navos.
What is the meaning of "u'Fi Resha'im Yevala Aven"?
Rashi: Sin will swallow him.
R. Yonah #1: He hides sin. This is like "Im Amar Ish Ki Yevula" (Iyov 37:20). A Rasha - one who sins in deed because his Yetzer overpowers him - will not testify Sheker about his colleague. His way is opposite. Even if he sees sin, he does not tell. It is not good in his eyes that people rebuke for sins and eradicate evil, for perhaps also he will be caught. Both of these Midos are bad - hiding sins that they see, and prosecuting liability; the latter is worse, like the next verse proves. It brings to false testimony, the harshest Aveirah, for it destroys the land.
R. Yonah #2: This is like Iyov said, "Im Tamtik b'Fiv Ra'ah 1 " (20:12).
Malbim: The mouths of evil judges cover up sin.
Metzudas David (20:12): If evil counsel is sweet in his mouth (good in his eyes).
