Why does the Torah now write "Eis Kol asher Tzivah Hashem aleichem ... "?
Rashi and Rashbam: To teach us that if someone acknowledges Avodah-Zarah, it is as if he denies the entire Torah.
And why does the Pasuk add "Min ha'Yom asher Tzivah Hashem ... "?
Rashi: To incorporate (in the denial) all the prophesies that all the Nevi'im prophesied.
Rashbam: This refers to "Anochi" and "Lo Yih'yeh l'cha", which preceded all the other Mitzvos.
Why does the Torah write "ve'Lo Sa'asu ... ", implying that it is referring to someone who fails to perform a Mitzvas Asei?