This week's Torah reading, Yitro,

This week's Torah reading, Yitro, narrates the giving of the Torah at Mount Sinai. About this central event in the history of the Jewish people the Torah states, "And G-d spoke all these words, saying." Our commentators ask a logical question: What is the meaning of the seemingly superfluous word "saying"?Throughout the Torah, wherever the word "saying" appears, the intent is for those words to be transmitted and repeated to those Jews who were not present at the time when G-d uttered them.
However, at the giving of the Torah, every single Jew was present. Everyone was there at Mount Sinai, everyone heard the Ten Commandments - even the souls of Jews yet to be born in future generations were present. Why then, in this instance, does the Torah employ the word "saying"?
The Maggid of Mezeritch, Rabbi Dov Ber, successor of the Baal Shem Tov, answered this question as follows:
"Vayedabeir - And G-d spoke" alludes to the Ten Commandments.
"Leimor - saying" alludes to the Ten Utterances by which G-d created the world.
The intent of the verse "And G-d spoke all these words, saying" is that the Torah was given for the purpose of drawing down the Ten Commandments into the Ten Utterances of the physical world, i.e., that the light of Torah would illuminate the world to such an extent that it is perceived on the physical plane of existence.
This job was given to the Jewish people when G-d gave them His Torah. Our task as Jews is to cause the light of Torah ("And G-d spoke") to illuminate the world ("saying"). We must never think that the Torah and the world are two separate entities. It isn't enough to conduct ourselves according to Torah when studying and praying. Rather, the light of Torah must be brought down to even our most mundane affairs. Everything a Jew does, no matter how worldly, must be carried out in accordance with the Torah's dictates and performed in a spirit of holiness.
This, then, is the core of the giving of the Torah: bringing the light of Torah, the Ten Commandments - "And G-d spoke" - not only into the realm of Torah, but also into the realm of physical existence, into the world that was created by the Ten Utterances - "saying."

Adapted from Likutei Sichot, Volume 1