What Is Tefillin? A Complete Guide to Jewish Phylacteries

The mitzvah of tefillin comes directly from the Torah. In four separate passages, the Torah commands Jewish men to bind the words of God 'as a sign upon your hand and as frontlets between your eyes.' These passages — written on parchment and placed inside specially constructed leather boxes — are the tefillin worn today, essentially unchanged for over two thousand years.

Tefillin are not merely symbolic. They are a direct physical fulfillment of a biblical commandment, on the same level as mezuzah, Shabbat candles, or kosher food. Every element — the leather, the parchment, the ink, the shape of the boxes, the knots, and the letters themselves — is governed by precise halachic rules codified in the Talmud and Shulchan Aruch. A single error in any component can render the entire pair invalid.

Each of the two boxes (called batim) contains parchment scrolls known as parshiot. These are not printed — they are written entirely by hand, letter by letter, with a quill or reed pen using special black ink on parchment made from the skin of a kosher animal.

The same four Torah passages appear in both boxes: (1) Kadesh (Shemot 13:1–10) — the commandment to remember the Exodus; (2) Vehaya ki yeviacha (Shemot 13:11–16) — the obligation to tell future generations; (3) Shema (Devarim 6:4–9) — the central declaration of Jewish faith; and (4) Vehaya im shamo'a (Devarim 11:13–21) — the reward and responsibility of observing God's commandments. Each passage must be written in order, with perfect letters, on a single continuous piece of parchment. The writing must be done with full intent (kavanah) for the mitzvah of tefillin. A printed photocopy, even if accurate, is entirely invalid.

Tefillin consist of two physically separate pieces that are worn together. The arm tefillin, called shel yad (literally 'of the hand/arm'), is a single-compartment box strapped to the bicep of the weaker arm — the left arm for right-handed men, the right arm for left-handed men. From the box, a long leather strap (retzuah) is wrapped seven times around the forearm and then wound around the hand and fingers in a precise pattern.

The head tefillin, called shel rosh ('of the head'), is a four-compartment box placed on the forehead, centered between the eyes, with the front edge resting just above the hairline. Its strap is knotted at the base of the skull and hangs down in front of each shoulder. Both boxes must be perfectly square, made from a single piece of leather or a single hide (depending on the grade), and painted black.

The order matters: the arm tefillin is always donned first, followed immediately by the head tefillin. Removing them reverses the order — head first, then arm. For the full step-by-step, see How to Put On Tefillin.

Jewish men from the age of Bar Mitzvah (thirteen) wear tefillin every weekday morning during the Shacharit prayer service. The obligation applies every day except Shabbat and major Jewish holidays (Yom Tov), because those days themselves serve as the 'sign' between God and the Jewish people. Tefillin are also not worn on Tisha B'Av morning or during the intermediate days of mourning (shiva).

In many communities, boys begin wearing tefillin one to three months before their Bar Mitzvah to learn the practice under guidance. This is an excellent time for a father, rabbi, or Sofer STaM to teach the boy the correct technique, blessings, and care. Rabbi Levi Backman offers one-on-one tefillin instruction for Bar Mitzvah boys across Miami and South Florida.

Not every scroll that looks like a tefillin scroll is kosher. The laws of Safrut (Jewish scribal arts) are extraordinarily precise. Every letter must be shaped according to traditional forms. Letters may not touch each other. The spacing between words and lines must follow exact measurements. The parchment must be processed specifically for sacred use. Even the quill must come from a kosher bird or be a reed prepared for the purpose.

Only a Sofer STaM — a scribe certified in the writing of Torah scrolls, tefillin, and mezuzot — has the training to produce valid tefillin parshiot. Even then, every pair of tefillin should be independently verified before use. Many tefillin sold online or through non-specialist retailers contain mass-produced or machine-printed parshiot that are not kosher, despite authentic-looking batim.

If you are unsure about the kosher status of your tefillin, the only safe path is to bring them to a certified Sofer STaM for inspection. In Miami, Rabbi Levi Backman verifies tefillin parshiot, batim, and retzuot with full written certification. Schedule a tefillin check.

The boxes themselves (batim) come in different grades, and the grade matters for both halachic validity and durability. The three main categories are peshutim, dakkot, and gassot.

Peshutim (simple) are the most basic. They are constructed from multiple strips of leather glued or stitched together. While kosher when properly made, they are less durable and more susceptible to warping or cracking over time.

Dakkot (thin) are a step up. They are made from a single piece of thinner leather stretched and formed over a mold. They look more refined than peshutim and hold their shape better, though they are still relatively lightweight.

Gassot (thick) are the premium standard. They are made from a single thick hide that is pressed and molded into shape, creating boxes that are extremely durable, maintain perfect squareness for decades, and are considered the most halachically beautiful. Gassot tefillin are the recommended choice for Bar Mitzvah and for anyone who plans to wear tefillin daily for life. They cost more upfront but can last generations with proper care.

Regardless of the grade of batim you choose, what matters most is that the parshiot inside are kosher, hand-written, and verified by a certified Sofer STaM. For kosher tefillin verified by Rabbi Levi Backman in Miami, see our tefillin sale page.

Tefillin are subjected to daily handling, rolling and unrolling, body heat, sweat, and environmental conditions. Over time, the internal parchments can develop cracked letters, faded ink, or moisture damage. The retzuot can dry out, crack, or lose their required black color. The batim can warp, chip, or lose their square shape. Any of these issues can invalidate the tefillin.

Jewish law recommends checking tefillin at least twice every seven years. In climates like Miami's — with intense heat, high humidity, and salt air — more frequent checking is advisable. Many Miami families choose to inspect tefillin every three to four years, or even annually before Rosh Hashana as part of their Elul preparation. If tefillin were exposed to water, extreme heat, or a long period of disuse, they should be checked before the next use.

A proper check involves opening the batim, examining each of the four parshiot under magnification, inspecting the stitching and paint on the boxes, and checking the retzuot for dryness, cracking, and blackness. Only a certified Sofer STaM can perform a complete inspection.

Rabbi Levi Backman is a Certified Sofer STaM serving Miami, Aventura, Miami Beach, Bal Harbour, Surfside, Sunny Isles, and Hallandale. He sells fully verified kosher tefillin in all grades — peshutim, dakkot, and gassot — with written kosher certificates for every pair. He also provides complete tefillin checking services: parshiot, batim, and retzuot inspected under magnification with full documentation.

For Bar Mitzvah families, Rabbi Levi offers curated packages that include tefillin, tallit, custom bags, a placement mirror, and a siddur — with one-on-one instruction for the new Bar Mitzvah boy. Browse tefillin for sale or schedule a professional check.

WhatsApp Rabbi Levi at 845-729-1459 for questions, appointments, or a same-day quote. Every pair of tefillin is fully verified by a certified Sofer STaM before delivery.