The Talmud makes no mention of how many times one should wrap the straps of tefillin around the arm, but the widespread custom is to do so seven times (in addition to first wrapping them around the biceps and later the fingers).1
The ubiquity of this custom can be credited to the Kabbalists, specifically Rabbi Isaac Luria, known as the the Arizal (1534–1572).
The Seven Maidservants
The Arizal explains that wrapping the tefillin around the arm seven times corresponds to the verse in the book of Esther2 that relates how Esther was given “seven maidens fitting to give her from the king’s house . . .”3
The purpose of tefillin is to bind our mind and emotions to G‑d. The mind is represented by the tefillin of the head, and the emotions are represented by the positioning of the arm tefillin near our hearts, the seat of emotion. Devoting our emotions to G‑d—i.e. developing a love and awe for the Creator— impacts our behavior; thus, the emotive tefillin are placed on the arm, which symbolizes action.
Tefillin are a symbol of the loving relationship between the Jewish nation and G‑d, which is analogous to the relationship between a husband and wife. Seven blessings are recited at a wedding ceremony, and many have the custom for the bride to circle the groom seven times. Accordingly, when we put on tefillin, the straps are wrapped around the arm seven times.8 9
(This is also why we additionally wrap the tefillin straps around our fingers, representing the ring a husband gives his wife under the chuppah.10 Indeed, some have the custom, while wrapping the strap around their fingers, to recite the verse “And I will betroth you to Me forever, and I will betroth you to Me with righteousness and with justice and with loving-kindness and with mercy. And I will betroth you to Me with faith, and you shall know the Lord.”11)
Seven Coils = Seven Words
The seven coils of the arm tefillin correspond to the seven words in the verse12 “פּוֹתֵ֥חַ “אֶת־יָדֶ֑ךָ וּמַשְׂבִּ֖יעַ לְכָל־חַ֣י רָצֽוֹן– “You open Your hand and satisfy every living thing [with] its desire.”13
(This verse is considered a central point of our daily prayers. In fact, we recite Ashrei in our daily prayers because it contains this verse. Furthermore, unlike almost all other verses in our prayers, the halachah is that if one recited this verse without thinking about the intent of the words, he must repeat it.14)
When we put on tefillin, we are connecting our mind and heart to G‑d. Some therefore say that the seven coils relate to the seven words in the verse15“וְאַתֶּם הַדְּבֵקִים בַּה׳ אֱלֹקיכֶם חַיִּים כֻּלְּכֶם הַיּוֹם”—“But you who cleave to the L‑rd your G‑d are alive, all of you, this day.”16
Subduing the Evil Inclination
The Talmud tells us that throughout Scripture, the yezter hara—evil inclination—is referred to by seven names,17 each representing a different aspect of the evil inclination. We put the tefillin on our left—inferior—hand and wrap the straps around seven times to subdue the forces of impurity and our evil inclination, which resides in the left side of our body.18
Shabbat—The Other Sign
Our sages teach that we were given three signs that represent the covenant between G‑d and His people: Shabbat, circumcision and tefillin. Circumcision is constant, and tefillin are worn daily. The seven coils ensure that Shabbat is also represented every day.19
Seven Heavens—Seven Branches of the Menorah
When we put on tefillin, we connect with G‑d and draw down holiness and divine light into the world. Based on this, some explain that the seven coils represent either the seven heavens20 or the seven branches of the Menorah in the holy Temple, which brought spiritual light into the world.21
For more on the mitzvah of tefillin, visit Tefillin and Its Significance.