גַּם־מִיּוֹם֙ אֲנִ֣י ה֔וּא וְאֵ֥ין מִיָּדִ֖י מַצִּ֑יל אֶפְעַ֖ל וּמִ֥י יְשִׁיבֶֽנָּה׃ (ס)
自從有日子以來，我就是那一位；沒有人能從我手中救人。我要行事，誰能使它轉回呢？
Rashi
Even before the day I am He Not only that day was I alone, but even before it became day I am He alone.
Ibn Ezra
Before the day was, etc. I was God before the existence of day. Therefore, the word גם yea is added.