How should they be paid like their deeds?
Malbim: They spoke to me unlike their hearts, and wanted to destroy me, and I would not realize. So You should 'speak' to them, "Lo Yavinu El Pe'ulas Hashem" (verse 5) - make them think that You are building them, and really, You are destroying them! This is Midah k'Neged Midah!
What does "uch'Ro'a Ma'aleleihem" add?
Radak: Only You know that what is in their hearts, for You know hidden matters. Pay them according to their evil deeds, for You know their evil!
What is the difference between Pa'al, Ma'aseh and Ma'alal?
Malbim: Pa'al is engaging in a matter. Ma'aseh is completing it. Ma'alal is an act that comes from a nature in the Nefesh - a good or bad Midah.
What is the difference between Pa'alam and Gemulam?
Malbim: Gemul is always tied to love or hate. Hashem should punish for (a) the Pe'ulah (action), (b) the engagement in it and the means they used to carry it out, and (c) the bad Midah from which the act sprouted (anger, cruelty, pride...). Also, the Gemul should be according to the hatred; one who ambushes and murders is worse than one who kills via war. One who kills one who loves him and sits confident with him is worse than one who kills one who hates him. If one harshly pains his murder victim, this is worse.
