Sforno on Leviticus 19:5/ספורנו על ויקרא י״ט:ה׳

1וכי תזבחו, at this point the Torah explains that when G’d issued the very first of the Ten Commandments with the words: “I am the Lord your G’d, etc.,” (20,2) this meant that the Israelites must accept Him as the exclusive divine power in the universe. They are to do so without reservation, just as they did during the song of thanksgiving for their miraculous salvation after crossing the sea with dry feet, when they sang (Exodus 15,2) זה א-לי ואנוהו, אלוקי אבי וארוממנהו, “this is My G’d and I will enshrine Him, the G’d of my forefather and I will exalt Him.” Not only must the Jewish people accept G’d’s dictates and carry them out, but they must be concerned with preserving His great name and not even in their thoughts do anything which would desecrate this great name of His.