What is the meaning of "Gam mi'Yom Ani Hu"?
Rashi: Not only that day I was alone - also from that day I am alone.
Radak #1: Before there was day, i.e. before the world was. It says Gam, for it said "Higadti" and "v'Hishmati" (12) - in the early days, of your fathers. Also before that, before the world, Ani Hu. "Ume'Olam v'Ad Olam Atah Kel" (Tehilim 90:2), before there was a world. Since I am so, no one can save from Me, when I want to save a nation from a nation, or to harm them.
Radak #2: This is a long time that I am with you. "Me'Olam Shavarti Ulech" (Yirmeyah 2:20).
Malbim: Also before I revealed myself to you, I am alone.
Why does it say "Ef'al u'Mi Yeshivenah"?
Rashi: If I come to act, no one can stop me.
Radak: When I do an act, no one can turn it back.
Malbim: Also in the future I am alone; no one can oppose Me.
