A collection of relevant halachos regarding the Mitzvah of Tefillin mentioned in Parshas Vaeschanan from AskTheRav.com & Halacha2Go.com. by Yosef Yeshaya Braun, Mara D’asra and member of the Crown Heights Beis Din
Do I need Permission to Borrow Someone’s Tefillin?
We may use another’s tefillin if we do not have our own pair, since the halachah is, “Nicha lay l’inish layavid mitzvah bemamonay,” a person is glad when a mitzvah is done with his money or possessions. Therefore, we can assume that a person would not mind if his tefillin are used by another Jew to do a mitzvah. However, there are a number of conditions that must be met: Firstly, borrowing another’s tefillin without his knowledge and explicit permission should not become habitual; it should only be b’akra’ei, done temporarily, if we do not have our own tefillin for some reason. Secondly, we should put away the tefillin properly, and not leave them unwound. Thirdly, we may not take them out of the shul, even if we plan on bringing them back; we may use them only in the room where the owner left them. According to many opinions, we are required to put them back in the same spot where we found them. The fourth condition is that we can only make the assumption that a person would approve of our using his tefillin if he is not present; if the owner is present, we should ask express permission before using his tefillin. There is a minority opinion among poskim that even if a person yells, “I do not let you use my tefillin!” we may use them anyway, but the majority of poskim disagree. *
The Yud (Knot) of Tefillin
The knot that is shaped like a yud on the tefillin shel yad (the tefillin we bind on our arm) should always be touching the bayis (the box of the tefillin). According to some poskim this applies even when the tefillin are not in use. There are opinions that say that it’s sufficient if the yud touches the titura (the base), even if it does not touch the bayis itself. Certainly, it’s sufficient if part of the yud touches the bayis. We also have to make sure that all the retzuos (straps) of the tefillin, including the yud and the area of the kesher (knot) always remain black. However, it’s acceptable if they give a black impression. Some opinions are lenient even if they are mostly black. The part of the retzuah that goes into the kesher and is not outwardly visible need not be black. In addition, it’s important to make sure that the entire yud is the right size: at least the beginning of the yud where it protrudes from the knot should be a minimum of nine millimeters wide. #322*
Kashrus of Batim for Tefillin
The four compartments that make up the batim (the boxes which house the parchment) of the Tefillin Shel Rosh are molded to form a perfect square. However, according to many poskim, including the Alter Rebbe, they must be prudos mamash (totally detached from each other). Some poskim are lenient and rule that tefillin are kosher even if there is a small amount of glue between the compartments—as long as it’s not near the top and it’s minimal. The charitzim (grooves) on the outside of the batim — which indicate where the compartments are separated from each other — may not be charitzim mezuyafim (fake), and have to be in the proper place. To ascertain whether there are any issues with one’s tefillin they can be taken to a batim macher (a professional batim maker) to be examined and any concerns addressed. #348*
Distinguishing Between Rashi and Rabeinu Tam Tefillin
It is the widespread custom for men to don two pairs of tefillin: one with the four parshiyos (the selected portions of the Torah written on scrolls of parchment) in the order prescribed by Rashi (i.e. the portion of Shema before V’haya im shamoa), and the other pair in accordance with the opinion of Rabeinu Tam (V’haya im shamoa before Shema).
The tefillin shel rosh (placed on the head) are easy to tell apart as there are hairs protruding on the front of the bayis (the box encasing the parshiyos) to the right of the parsha containing V’haya im shamoa: On the Rashi tefillin that is between the third and fourth sections of the bayis, and on the Rabeinu Tam tefillin it is between the second and third sections (i.e. in the middle).
However, the tefillin shel yad (bound on the arm) are indistinguishable on the outside. Some poskim mention the custom of making the bayis of the tefillin d’Rabeinu Tam slightly smaller in order to tell them apart; however, that is not the common practice. In order to avoid confusing the two, it’s advisable to make some kind of indication on the protective box which covers the tefillin shel yad, or to cut the end of one of the retzuos (tefillin straps) in a way that will differentiate them. Of course, no mark should be made on the tefillin themselves. #451*
Should I buy Tefillin Straps that are Painted Black on Both Sides?
Traditionally, only one side of retuzos (tefillin straps), the outer side, is painted black. However, many sofrim (scribes) and Judaica stores have lately begun selling retzuos painted black on both sides, apparently based on a minority view of the Rishonim that they are more beautiful that way, and thus constitute a hiddur mitzvah (beautification of a mitzvah). This view may have a basis in kabbalah, as well.
However, it seems untoward to adopt a practice which follows a view that wasn’t practiced in the past. Indeed, poskim clearly state that the prevailing custom isn’t in accordance with this view. On the other hand, if one doesn’t do it on principle but rather for practical considerations, since retzuos that are painted on both sides are immersed in paint, and as a result the paint adheres better, it shouldn’t be a problem. #482* ■