Why does it say "Ma'asei Yadav Emes u'Mishpat"?
Radak: Ma'asei Yadav is what He did in the wars against the Goyim, to expel them from their land. In was not injustice, rather, Emes (to fulfill His word to Avraham) and Mishpat (they did not deserve to live there, due to their evil deeds). "Ki Lo Shalem Avon ha'Emori Ad Henah" (Bereishis 15:16) teaches that when their sin was complete, He expelled them from their land. The land is "Admas ha'Kodesh" (Zecharyah 2:16); those who do abominations cannot remain there - "Ki b'Rish'as ha'Goyim ha'Eleh Hashem Elokecha Morisham Mipanecha u'Lema'an Hakim Es ha'Davar Asher Nishba Hashem la'Avosecha" (Devarim 9:5).
Malbim (6): He informed them that His deeds are Emes and Mishpat. This is the inner strength that sustains the entire creation. He arranged the entire creation so people will recognize from it Hashem's existence and unity, and the true Emunah. Without Emes and Mishpat, the creation is like a body without a Neshamah. The Kena'ani annulled Emes and Mishpat, therefore they could not last in the world. Hashem commanded to wipe out memory of them 1 , just like we get rid of a dead body.
I do not know where He commanded so. We sent three letters to the Kena'anim; if they will abandon idolatry and become Gerei Toshav, they may remain in the land. They may flee (like the Girgashim did), and there is no Mitzvah to kill them! (PF)
Why does it say "Ne'emanim Kol Pekudav"?
Radak: All His judgments are faithful; there is no injustice in them.
