The number “620” can also be represented as 613 commandments established by the Torah, and 7 commandments established by the sages.
The Alter Rebbe explains in the book of “Tanya”:
– And the 613 commandments of the Torah, together with the seven commandments of our Rabbis, combine to total the numerical equivalent of keter (“crown”), which is the supernal will,
[Will is called a crown, for like a crown, it encompasses the head and brain; Iggeret Hakodesh, loc. cit., where this is discussed at length.]
which is clothed in His wisdom,
[Thus, in addition to the fact that Torah is G-d’s wisdom, which in its descent in the downward progression of Worlds becomes the shrine of the Holy of Holies for the Shechinah, there is the additional quality of its being the supernal will, which is even loftier than wisdom. This is uniquely found in the Halachah and the mitzvot, as they are expressions of the supernal will].
and they (G-d’s will and wisdom) are united with the light of the Ein Sof in a perfect union. (Tanya, Chapter 53)