פירוש על שמות 13:9

Behold, in the first night of Passover the Holy One of Blessing instructed that a person clarifies her/his mouth. The forces of the mouth are eating, drinking and speaking. And the Holy One of Blessing commanded the eating of matzah, the drinking of the [four] cups and with that the eating and drinking of the entire year is clarified, since these mitzvot will defend a person the entire year, so that prohibited things won't come to one's mouth. And regarding the force of speaking the Holy One of Blessing instructed the telling of the exodus from Egypt, and with that there is defense from speaking prohibited things all the year. And this is so that "The Torah of Ad-nai will be in your mouth" - that all forces of the mouth will be very clarified and, and full of words of Torah.

והיה לך לאות AND IT SHALL BE FOR A SIGN UNTO THEE — i. e. the Exodus from Egypt shall be to thee as a sign

AND IT SHALL BE FOR A SIGN UNTO THEE UPON THY HAND, AND FOR A MEMORIAL BETWEEN THINE EYES, THAT THE LAW OF THE ETERNAL MAY BE IN THY MOUTH; FOR WITH A STRONG HAND HATH THE ETERNAL BROUGHT THEE OUT OF EGYPT. To be interpreted [properly, the verse must be transposed]: “And it shall be for a sign unto thee upon thy hand and for a memorial between thine eyes, that with a strong hand hath the Eternal brought thee out of Egypt, that the law of the Eternal may be in thy mouth.” The meaning thereof is that you are to inscribe the exodus from Egypt [in the phylacteries] upon your hand and between your eyes, and remember it always in order that G-d’s law be in your mouth, [so that you will] observe His commandments and teachings, for He is your Master Who redeemed thee out of the house of bondage.³⁹⁰Deuteronomy 13:6.