Musar su Esodo 13:9

[And in this manner I have explained the verse in Psalms 81:10: "There shall not be in you a strange god and you shall not bow down to a foreign god. (11) I am the L-rd your G-d who brought you up from the land of Egypt. Open wide your mouth and I will fill it." Now, ostensibly, it should first have been written "I am the L-rd your G-d, etc." and only then "There shall not be in you a strange god," as it is written in the Torah. Why is the order reversed? But, Chazal have told us (Shabbath 105b): "Which is the strange god in the body of a man? The yetzer hara." (In the beginning it incites him to commit transgressions which are not so severe; but, in the end, "transgression breeds transgression," and it permits him even to bow down to idols.) And the intent of the verse [in Psalms]: "I am the L-rd your G-d, etc." is: Have I not brought you up from the land of Egypt so that you receive the Torah, as it is written (Shemoth 3:12): "And this is the sign for you [Moses] that I have sent you. When you take out the people from Egypt, you will serve G-d on this mountain." For this [the receiving of the Torah] is the purpose of the exodus, as Rashi explains. Therefore, "open wide your mouth and I will fill it." This is like a rabbi's telling his disciple: "Open up your mouth and let your words shine forth." For the Holy One Blessed be He wishes to give each Jew a great share in the Torah. However, in truth, everything is dependent upon the power of the recipient, wherefore He says: "Open wide your mouth." That is, ready yourself to receive much, and I will fill it according to your widening. But this is prefaced by: When will this be fulfilled in you? When "there will not be in you a strange god," when the yetzer hara will not be a guest in your body. Then you will be able to open wide your mouth to Torah, and I will fill it. For it is to this end that I brought you up from the land of Egypt (As it is written (Ibid. 13:9): "And it shall be a sign upon your hand… so that the Torah of the L-rd shall be in your mouth.") But if there is a strange god in your body— that is, if it is full of lewd thoughts, G-d forbid, I will not be able to fulfill your wish to widen your mouth with Torah.

Memory is a very lofty quality and it is an instrument that strengthens all the commandments and all the Torah. Concerning the fringes, it is said, "And remember all the commandments of the Lord and do them … that ye may remember and do all My commandments" (Num. 15:39-40). Concerning the tefillin, it is said, "And it shall be for a sign upon thee upon thy hand, and for a memorial between thine eyes, that the law of the Lord may be in thy mouth" (Ex. 13:9). And it is written, "And thou shalt remember that thou wast a bondman in Egypt; and thou shalt observe and do these statutes (Deut. 16:12).

The reason that these numbers need to be found in the construction of the תפילין is the statement of the Talmud Kidushin 35, based on: למען תהיה תורת השם בפיך that the entire Torah is compared to תפילין (Exodus 13,9).