הלכה על שמות 3:12

It is from the roots of the commandment from the angle of the simple understanding [that it is] since the entire essence of Israel is only the Torah, and because of the Torah were the heavens and earth created, and as it is stated (Jeremiah 33:25), "Were it not for my covenant day and night, etc." And it is the essence and the reason that they were redeemed and left from Egypt - in order that they receive the Torah at Sinai, and fulfill it. And [it is] like God said to Moshe (Exodus 3:12), "And this will be the sign for you that I have sent you; when you take out the people from Egypt, you shall worship God on this mountain." And the understanding of the verse is [that] your taking them out from Egypt is a sign for you that you shall worship God on this mountain - meaning that you shall receive the Torah, which is the great principle for which they were redeemed and it is their ultimate good. And it is a great matter for them, more than freedom from slavery. And hence God made a sign of their leaving Egypt for the receiving of the Torah; as we always make what is secondary into a sign for what is the essence.