Exodus 13:16

16So it shall serve as a sign and a reminder on your [left] hand (arm) and as 13:16 Heb totaphoth, later renamed tefillin (“attachment”) but often called phylacteries (Gr “safeguards”) these came to be small cube-shaped leather pouches which contained tiny parchments of Ex 13:1-16 and Deut 6:4-9; 11:13-21. They were strapped to the forehead and the left forearm of Jewish men (or the right forearm, if a man was left-handed) in obedience to the commands in this verse and Deut 6:8. Phylacteries and the parchments contained in them were very artistically made, and are still worn today by observant Jews during morning services.frontlets between your eyes, for by a strong and powerful hand the Lord brought us out of Egypt.”