The first word of God on Sinai was Anoki, "It is I." It was not a Hebrew word, but and Egyptian word that Israel first heard from God. He treated them as did that king his home-coming son, whom, returning from a long stay over sea, he addressed in the language the son had acquired in a foreign land. So God addressed Israel in Egyptian, because it was the language they spoke. At the same time Israel recognized in this word "Anoki," that is was God who addressed them. For when Jacob had assembled his children around his death-bed, he warned them to be mindful of the glory of God, and confided to them the secrets that God would hereafter reveal to them with the word "Anoki." He said: "With the word 'Anoki' He addressed my grandfather Abraham; with the word 'Anoki' He addressed my father Isaac, and with the word 'Anoki' He addressed me. Know, then, that when He will come to you, and will so address, you, it will be He, but not otherwise." 
When the first commandment had come out of the mouth of God thunder and lightning proceeded from His mouth, a torch was at His right, and a torch at His left, and His voice flew through the air, saying: "My people, My people, House of Israel! I am the Eternal, you God, who brought you out of the land of Egypt." When Israel heard the awful voice, they flew back in their horror twelve miles, until their souls fled from them. Upon this the Torah turned to God, saying: "Lord of the world! Hast Thou given me to the living, or to the dead?" God said: "To the living." The Torah: "But they are all dead." God: "For thy sake will I restore them to life." Hereupon He let fall upon them the dew that will hereafter revive the dead, and they returned to life.
The trembling of heaven and earth that set in upon the perception of the Divine voice, alarmed Israel so greatly that they could hardly stand on their feet. God hereupon sent to every one of them two angels; on lay his hand upon the heart of each, that his soul might not depart, and on to lift the head of each, that he might behold his Maker's splendor. They beheld the glory of God as well as the otherwise invisible word when it emanated from the Divine vision, and rolled forward to their ears, whereupon they perceived these words: "Wilt thou accept the Torah, which contains two hundred and forty-eight commandments, corresponding to the number of the members of they body?" They answered: "Yea, yea." Then the word passed from the ear to the mouth; it kissed the mouth, then rolled again to the ear again to the ear, and called to it: "Wilt thou accept the Torah, which contains three hundred and sixty-five prohibitions, corresponding to the days of the year?" And when they replied, "Yea, yea," again the word turned from the ear to the mouth and kissed it. After the Israelites had in this wise taken upon themselves the commandments and the prohibitions, God opened the seven heavens and the seven earths, and said: "Behold, these are My witnesses that there is none like Me in the heights or on earth! See that I am the Only One, and that I have revealed Myself in My splendor and My radiance! If anyone should say to you, 'Go, serve other gods,' then say: 'Can one who has seen his Maker, face to face, in His splendor, in His glory and His strength, leave Him and become an idolater?' See, it is I that have delivered you out of the house of bondage; it is I that cleaved the seas before you and led you on dry land, while I submerged you enemies in the depths.  I am the God of the dry land as well as the sea, of the past as well as of the future, the God of this world as well as of the future worlds.  I am the God of all nations, but only with Israel is My name allied. If they fulfil My wishes, I, the Eternal, am merciful, gracious and long suffering, and abundant in goodness and truth; but if you are disobedient, then will I be a stern judge. If you had not accepted the Torah, no punishment could have fallen upon you were you not to fulfil it, but now that you have accepted it, you must obey it." 
In order to convince Israel of the unity and uniqueness of God, He bade all nature stand still, that all might see that there is nothing beside Him. When God bestowed the Torah, no bird sang, no ox lowed, the Ofannim did not fly, the Seraphim uttered not their "Holy, holy, holy," the sea did not roar, no creature uttered a sound
These words as well as the others, made know by God on Mount Sinai, were not heard by Israel alone, but by the inhabitants of all the earth. The Divine voice divided itself into the seventy tongues of men, so that all might understand it; but whereas Israel could listen to the voice without suffering harm, the souls of the heathens almost fled from them when they heard it.  When the Divine voice sounded, all the dead in Sheol were revived, and betook themselves to Sinai; for the revelation took place in the presence of the living as well as of the dead, yea, even the souls of those who were not yet born were present. Every prophet, every sage, received at Sinai his share of the revelation, which in the course of history was announced by them to mankind.  All heard indeed the same words, but the same voice, corresponding to the individuality of each, was God's way of speaking with them. And as the same voice sounded differently to each one, so did the Divine vision appear differently to each, wherefore God warned them not to ascribe the various forms to various beings, saying: "Do not believe that because you have seen Me in various forms, there are various gods, I am the same that appeared to you at the Red Sea as a God of war, and at Sinai as a teacher."