The phylactery  is a leather box or case containing pieces of parchment in the form of miniature scrolls on which are hand-written in Masoretic Hebrew from the texts of
- Exodus 13:1-16; Deuteronomy 6:4-9; 11:13-21.
In a literal interpretation of Exodus 13:9, Exodus 13:16 and Deuteronomy 6:8; Deuteronomy 11:18, observant Orthodox Jews wear phylacteries containing small scrolls of these four scriptures. According to a literal interpretation of the text the phylactery is (supposed to be) bound on the forehead between the eyebrows ("between the eyes"), and on the forehand, and is normally held in place with a leather headband, or with a long leather strip wound round the arm in a prescribed pattern according with tradition. Usually, it is carried on the person for convenience, often kept close at hand in a pouch on the belt or under the shirt, coat or garment. In New Testament times phylacteries were worn, bound with thongs, by Jewish men during prayer times, except on the Sabbath and feast days. The actual custom, however, as it has developed in practice over the centuries is to wear the principal phylactery on the head positioned more conveniently several inches above the nose and eyebrows near the top of the forehead just back of the normal position of the hairline close to the top of the head held in place with a leather band, and position one for the hand on the upper arm instead, so that when the worshiper crosses his arms the Scriptures contained in the phylactery would be close to the heart. They are primarily worn at times of prayer. Because of the sacredness of the scriptures and the direct association with prayer to God, they were also regarded as amulets of protection against evil spirits.
Phylacteries are mentioned only once in the New Testament, in Matthew 23:5. Jesus condemned those Jews who called attention to themselves by wearing larger than usual phylacteries as a mark of greater piety.
Frontlets are mentioned only thrice in the KJV Old Testament, in Exodus 13:16 and in Deuteronomy 6:8 and 11:18.
Small scrolls called mezuzah (Hebrew מזוזה, "doorpost") inscribed with Deuteronomy 6:4-9 and 11:13-21 are placed in a container attached to the doorjambs of some Jewish homes; and this container with the mezuzah within it is only removed when the whole family abandons their home to depart to another place.
In the context of the literal sense of scripture it was the sacrifice of all the firstborn males of the cattle and the redemption of the firstborn males of the people of Israel that was itself to be as a mark on the hand or frontlets (armor) between their eyes. (Exodus). Loving the LORD their God with all their heart, and with all their soul, and with all their might, and upon their hearts the words the LORD their God commanded them, teaching them diligently to their children, and talking of them when they sit in their houses, and when they walk along the roads, and when they lie down, and when they rise, was itself to bind them as a sign upon their hands, and as face-shields between their eyes, and to write them on the doorposts of their houses and on their gates. (Deuteronomy). And laying up the words of the LORD their God in their heart and in their soul is itself to bind them as a sign upon their hand, that they be as frontlets, face-shields, between their eyes, and teaching them to their children, talking of them when they are sitting in their houses, and when they are walking by the road, and when they lie down, and when they rise, is itself to write them upon the doorposts of their houses and upon their gates. For if they would have been careful to do all the commandment which God commanded them to do, loving the LORD their God, walking in all his ways, and cleaving to him, no one would have been able to stand against them. (Deuteronomy).According to the New Covenant, loving the Lord God with all the whole heart and soul and mind and strength and loving others as oneself is the fulfillment of the law of the Lord. This is found in Matthew 22:36-40; Mark 12:28-34; Romans 13:8-10; Galatians 5:14; James 2:8. It is also found in John 13:34-35; 15:12-14, 17; 1 John 3:23-24; 4:7-8, 21; 5:2-3; 2 John 6, 9-11. St. Paul expressed the language of the law of the Lord as frontlets of armor between the eyes when he wrote:
"He who loves his neighbor has fulfilled the law" Romans 13:8
"For the whole law is fulfilled in one word 'You shall love your neighbor as yourself'." Galatians 5:14
"Let us therefore cast off the works of darkness and let us put on the armor of light" Romans 13:12
"By the word of truth, by the power of God, by the armor of righteousness on the right hand and on the left" 2 Corinthians 6:7
"Put on the whole armor of God, that you may be able to stand against the wiles of the devil. . .take unto you the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand." Ephesians 6:11, 13
"That the God of our Lord Jesus Christ, the Father of glory, may give to you the spirit of wisdom and revelation in the knowledge of him: the eyes of your understanding being enlightened" Ephesians 1:17-18
(And regarding all those under the law who had turned aside, he said,) "There is no fear of God before their eyes." Romans 3:18
Christians who constantly carry the Holy Bible or a small New Testament with them or a Rosary, or wear a cross, crucifix or religious medal, have been accused of regarding them as amulets of protection against evil and Satan, as the Jews regarded their phylacteries as shields against spiritual danger.
- http://biblehub.com/hebrew/2903.htm טופפה towphphah "go around, bind"
- http://biblehub.com/greek/5440.htm φυλακτήριων phylacterion "guard-case"
- Matthew 23:5 parallel versions and passages
- Matthew 23:5 multiple commentaries
- PHYLACTERIES ("tefillin"). By: Executive Committee of the Editorial Board., Julius H. Greenstone, Joseph Jacobs, Ludwig Blau, Emil G. Hirsch - Jewish Encyclopedia (jewishencyclopedia.com)