Thou shalt give all diligence, and use all means, to keep them in thy remembrance, as men ofttimes bind something upon their hands, or put it before their eyes, to prevent forgetfulness of a thing which they much desire to remember: compare Proverbs 3:3, Proverbs 6:21 7:3. See Poole on "Exodus 13:16".
Related Commentaries of Deuteronomy 6:8
Deuteronomy 6:8
8 And thou shalt bind them for a sign upon thine hand, and they shall be as frontlets between thine eyes.