The Revelation at Sinai is the fulfillment of Hashem’s plan for the people of Israel. Everything that occurred up to this point — from the descent to Egypt, the enslavement and oppression, the plagues, the splitting of the Sea of Reeds and the liberation — were all in preparation for the nation’s encounter with Hashem.

After three days of purification, as the Divine Presence descends in fire to the top of the smoking, quaking mountain, the people are ready for their collective prophecy:
And Moshe brought the people out from the camp to meet G-d, and they stood upright at the foot of the mountain…
And the prophecy is heard:
And G-d spoke all these words, saying: I am Hashem, your G-d, Who brought you out of the land of Egypt, from the house of slaves… (Shemot 19:17, 20:1-2).

It was known from the beginning that this meeting would take place. While still in Egypt,
And Moshe said to G-d, “Who am I that I should go to Pharaoh, and that I should bring forth the Children of Israel out of Egypt?” And He said, “Because I shall be with you; and this is the sign to you that I have sent you; when you shall bring the people out of Egypt, you shall serve (TA’AVDUN) G-d on this mountain” (Shemot 3:11-12).

But, how can the receiving of the Torah, in which the people were essentially passive, be regarded as the realization of you shall serve (TA’AVDUN) G-d?

Indeed, says Ibn Ezra (in his long commentary), TA’AVDUN is not completely achieved until later (24:4-8), when Moshe writes down the laws, builds an altar, and the people offer sacrifices, followed by Moshe’s sprinkling blood upon the altar, reading the Book of the Covenant, and the people’s committing themselves to obey Hashem. Serving Hashem, as Moshe had said to Pharaoh (8:23), means sacrifices and commitment.

However, most other commentaries understand that the very receiving of the Torah is the actualization of TA’AVDUN. Rashi (3:12) emphasizes that Hashem did not rescue them from Egypt because they deserved it, but since “I have a great thing (consequence) for this taking out,” namely, because they are meant to receive the Torah.

Ramban makes the point that Moshe was concerned lest the people would not follow him to Canaan. Once they receive the Torah, however, they become committed to Hashem, which is the service embodied in TA’AVDUN; this, in turn, will make the people committed to following and obeying Moshe (see 19:9). [This is the position adopted by Rambam in the Laws of the Fundamentals of the Torah 8:2.]

Hirsch (Rabbi Shimshon Raphael Hirsch, 1808-1888) anticipates the entire difficulty by translating TA’AVDUN ET HA’ELO-IM as
“You shall become the servants of G-d.”
This will occur through receiving the Torah.

Heretofore, prophecy was the domain of individuals. Now, for the first and only time in human history, an entire nation experiences prophecy. And, in this instance as in all others, the encounter with Hashem — TA’AVDUN ET HA’ELO-IM — takes the form of hearing the Divine Will expressed in the form of mitzvot, commandments.

This profound idea is developed by Rabbi Dr. Norman Frimer (1916-1993), in his contribution to the 1966 book, The Conditions of Jewish Belief:
“In almost every instance in the Pentateuch where the will of God directly confronts man, the event of revelation is not expressed merely as mysterious divine presentness without content or specificity. Invariably the Torah associates the Godly call with commission and command.”
Hashem’s initial communication to the prophet is more than just the contemplation of the mysterium tremendum; it is in the form of a command, which establishes the nature of the prophetic experience.

Hashem’s first address to Adam, and thus to the human race, is
And Hashem G-d commanded the man, saying, “From every tree of the garden may you indeed eat; but from theTree of the Knowledge of Good and Evil you shall not eat of it . . .” (Bereishit 2:16-17).
Hashem orders Noach
“Make for yourself an ark of gopher wood . . .” (6:14).
Hashem commands Avra(ha)m
“Go from your country and from your birthplace and from your father’s house to the land which I will show you” (12:1).
The first recorded prophecy to Yitzchak is
“Do not go down to Egypt; dwell in the land which I shall tell you of” (26:2).
Yaakov translates his vision of the ladder into commitment:
And Yaakov vowed a vow, saying, “ . . . this stone which I have set as a memorial shall become a house of G-d, and everything that You will give me I shall surely tithe to You” (28:20-22).
And, at the burning bush, Moshe is charged:
“Do not approach here. Remove your shoes from upon your feet, because the place upon which you stand is holy ground” (Shemot 3:5).
Thus mankind learns that Hashem makes demands and sets standards.

Rabbi Frimer continues:
“A similar pattern confronts us as we examine the record of the Sinaitic stand. On this occasion, to be sure, not just select individuals are graced with the gift of prophecy. A whole community participates in a national divine-human meeting. In fact, the revelation at Sinai itself, entailing a second creation, gives birth to a new people of Israel and constitutes it at one and the same time as both faith and nation. . . .
Once again, however, the Torah does not describe this “invasion” of the Timeless into the timely, the Eternal into the momentary, merely in the universal terms of “Presence as power,” . . . not a call to some ineffable spiritual ecstasy or mystical union. It is boldly set forth in a detailed outline of daily living, seeking to interpenetrate every nook and cranny of experience with holiness.”

Living a life in accordance with the commands of the Torah is the highest service to Hashem. It is living a life in response to prophecy.