A Kabbalistic meditation preserved in Kitzur Shnei Luchot ha-Berit teaches that the 613 commandments of the Torah form a covenant between the Holy One, blessed be He, and Israel — and the bond is woven into the very letters of God's names. Scripture says (Exodus 3:15), This is My Name, and this is My memorial.
The sages took the phrase apart. The Hebrew letters of "My Name" combined with the letters Yeh-o add up by gematria to 365 — the number of negative commandments, which match the days of the solar year. The letters of "My memorial" combined with Vah add up to 248 — the number of positive commandments, matching the limbs of the human body. Together: 365 plus 248 equals 613. Creation, body, and mitzvah are the same equation written in three alphabets.
The mystics went further. The soul, they taught, is "a portion of God from above" — and this is hinted at by the three levels nefesh (breath), ruach (spirit), and neshamah (soul). The initial and final letters of these three words together total 613. The middle letters together spell the divine titles "Lord, Almighty, God."
And the soul of Moses our teacher — peace be upon him — embraced within itself the souls of all Israel. The phrase "Moshe Rabbeinu" itself adds to 613, and so does the phrase "Lord God of Israel." The Zohar teaches that when a Jew keeps a mitzvah, he is not obeying an external rule — he is repairing a circuit that runs through Moses, through his own soul, and back to the Name engraved at the burning bush.