By adopting and regulating customary usages (e. g. Egyptian) Moses provides at once a check on superstition and a means of keeping the Divine Law in memory. On the “frontlets,” the “phylacteries” of the New Test. Matthew 23:5, see Exodus 13:16. On Deuteronomy 6:9; Deuteronomy 11:20 is based the Jewish usage of the mezuzah. This word denotes properly a door-post, as it is rendered here and in Exodus 12:7, Exodus 12:22; Exodus 21:6 etc. Among the Jews however, it is the name given to the square piece of parchment, inscribed with Deuteronomy 6:4-9; Deuteronomy 11:13-21, which is rolled up in a small cylinder of wood or metal, and affixed to the right-hand post of every door in a Jewish house. The pious Jew touches the mezuzah on each occasion of passing, or kisses his finger, and speaks Psalms 121:8 in the Hebrew language.
Related Commentaries of Deuteronomy 6:8
Deuteronomy 6:8-9
8 And thou shalt bind them for a sign upon thine hand, and they shall be as frontlets between thine eyes.
9 And thou shalt write them upon the posts of thy house, and on thy gates.