"Beware Lest Thou Forget"

So that the children of Israel would not forget the Lord their God, he asked them to bind the words on their hand and for frontlets between their eyes and to write them on their doorposts.  He asked them to say them in the morning when they rise up and at night when they went to bed.

To fill this commandment the children of Israel made Phylacteries which they wore on their foreheads and bound to their right arm and wrapped them down to their hand.  The verses from Deuteronomy 6:4-9 and 11:13-21 were written on parchment and placed within the box.

These verses were called the Shema, which means HEAR named after the first word of verse 4 which was HEAR.

The box that contained these scriptures and nailed to their doorpost was called a Mezuzah.  On entering the home one would touch the Mezuzah as shown in the picture below.  

Deut  6:4-9
 4  Hear, O Israel: The LORD our God [is] one LORD:
 5 And thou shalt love the LORD thy God with all thine heart, and with all thy soul, and with all thy might.
 6 And these words, which I command thee this day, shall be in thine heart:
 7 And thou shalt teach them diligently unto thy children, and shalt talk of them when thou sittest in thine house, and when thou walkest by the way, and when thou liest down, and when thou risest up.
 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.

Deut  11:13-21
 13 And it shall come to pass, if ye shall hearken diligently unto my commandments which I command you this day, to love the LORD your God, and to serve him with all your heart and with all your soul,
 14 That I will give [you] the rain of your land in his due season, the first rain and the latter rain, that thou mayest gather in thy corn, and thy wine, and thine oil.
 15 And I will send grass in thy fields for thy cattle, that thou mayest eat and be full.
 16 Take heed to yourselves, that your heart be not deceived, and ye turn aside, and serve other gods, and worship them;
 17 And [then] the LORD'S wrath be kindled against you, and he shut up the heaven, that there be no rain, and that the land yield not her fruit; and [lest] ye perish quickly from off the good land which the LORD giveth you.
 18  Therefore shall ye lay up these my words in your heart and in your soul, and bind them for a sign upon your hand, that they may be as frontlets between your eyes.
 19 And ye shall teach them your children, speaking of them when thou sittest in thine house, and when thou walkest by the way, when thou liest down, and when thou risest up.
 20 And thou shalt write them upon the door posts of thine house, and upon thy gates:
 21 That your days may be multiplied, and the days of your children, in the land which the LORD sware unto your fathers to give them, as the days of heaven upon the earth.

Also, in Numbers 15:38-41 the Lord commanded them to wear the prayer shawl.

Num  15:38-41
 38 Speak unto the children of Israel, and bid them that they make them fringes in the borders of their garments throughout their generations, and that they put upon the fringe of the borders a ribband of blue:
 39 And it shall be unto you for a fringe, that ye may look upon it, and remember all the commandments of the LORD, and do them; and that ye seek not after your own heart and your own eyes, after which ye use to go a whoring:
 40 That ye may remember, and do all my commandments, and be holy unto your God.
 41 I [am] the LORD your God, which brought you out of the land of Egypt, to be your God: I [am] the LORD your God.

Pictured below are Phylacteries, Prayers Shawl, and a Mezuzah: