What is "ha'Amnum"?
Refer to 58:2:2:1.
Rashi: It is an expression of Emunah.
Why does it say "[ha'Amnum] Elem Tzedek Tedaberun [Meisharim]"?
Chulin 89a: One's Umnus (profession) in this world is to make himself like an Ilem (mute). Do not say that this applies even to Torah - "You should speak Tzedek." Do not say that may become haughty - "Meisharim". (One should be like a Mishor, i.e. flat land.)
Rashi: Was mute from your mouths (you did not say) the Tzedek that you should have spoken (to prove that I do not seek to kill Sha'ul) and the straightness that you should have judged.
Radak: "Elem" is a collection, like "Me'almim Alumim" (Bereishis 37:7). It addresses Avner and Sha'ul's other officers, who judged David to be Mored b'Malchus, and that Sha'ul properly chases him to kill him. Had they prevented him, he would not have pursued David. David says, when you gather for my judgment, or that of other oppressed people like me, if you will speak Tzedek b'Emes and judge straightly, you would not do so (call me Mored b'Malchus).
Malbim: [Can one believe] that two opposites can be united in one matter?! With your mouths you speak Tzedek, but "in the heart you do injustice" (verse 3).
Why does it say "Meisharim Tishpetu Bnei Adam"?
Malbim: You judge people to do straightly, and not Chamas (extortion) and theft, and you yourselves "openly pave the way for Chamas of your hands" (verse 3)! The act contradicts the speech!
