I. Arranging Tefillin
If you view each mitzvah as an opportunity, then you will certainly immediately fulfill any available mitzvah. This attitude is described in the Talmud as “Ein ma’avirin al ha-mitzvos, we do not pass over a mitzvah” (link). I follow a curious practice in removing my tefillin that, I was taught, exemplifies this attitude in view of a twentieth century change in technology.
The Gemara (Yoma 33b) states that you may not pass over your hand-tefillin. Tosafos (ad loc., sv. avurei) offers three explanations of this passage, among them Rabbenu Tam’s ruling that you must arrange your tefillin in their bag so that when you remove them in the morning your hand first reaches the hand-tefillin. The reason is that the rule, based on a biblical inference, is that you must first put on your hand-tefillin before your head-tefillin (Menachos 36a). If you mistakenly lift your head-tefillin first, you would theoretically have to put it on first so as not to pass over that mitzvah. However, because of the above rule, you must put it down and take your hand-tefillin first.
To avoid this awkward setting aside of the laudatory attitude toward the mitzvah, you should arrange your tefillin in their container so this situation never arises. Make sure your hand always reaches your hand-tefillin first. This is all standard practice, as is arranging your tallis in front of your tefillin so you put it on first (Shulchan Arukh, Orach Chaim 25:1, 6). Common practice is to place your hand-tefillin on the left side of the bag so that your right hand reaches it first. However, I was taught to do something extra.
II. Unzipping Tefillin
R. Feivel Cohen once taught that the rule must be modified slightly. Allow me to offer my explanation of his position. The Arukh Ha-Shulchan (ad loc., par. 19 – link) explains that when you open your tefillin bag, both of your tefillin are set before you and you naturally reach to the left, where your hand-tefillin lie. However, technology has changed since then. The zipper was invented in 1917 (link) and quickly became standard on clothing. At some point, the zipper also became standard on tefillin bags. When I unzip my tefillin bag, my hand starts on the left, near the hand-tefillin, but ends on the right, near my head-tefillin. After I unzip the tefillin bag, my hand is closest to the head-tefillin and I should, at least theoretically, grab the opportunity to put on my head-tefillin. For the above reason, I must instead set aside that attitude and pass over the head-tefillin for the hand-tefillin.
R. Feivel Cohen did not mention the technology issue but ruled that the above practice is sub-optimal. He therefore said that you should only unzip your tefillin bag halfway at first, so your hand is right next to the hand-tefillin while the head-tefillin remains behind a closed zipper. In this way, you need not pass over the head-tefillin. While I recall him quoting a specific proof, which we will address soon, this still struck me as odd. Nevertheless, since I attended his synagogue I adopted the practice, which I continue today over fifteen years later.
III. A Different Approach
I recently came across an explicitly dissenting view. The prolific R. Menachem Kasher published his first article at the age of 15 on the issue of refraining from passing over a mitzvah. He received a lengthy response from R. Chaim Moshe Elyashar of Jerusalem, whose name I do not recognize. R. Kasher published this exchange in his Divrei Menachem (vol. 1, nos. 37-38 – link). R. Elyashar quotes the Shorshei Ha-Yam, a book which I also fail to recognize, as saying the following: The rule of not passing over a mitzvah only means that if you are ready to perform that mitzvah, do not get sidetracked and do something else. Therefore, if you are reaching for one of your tefillin to put on and accidentally take your head-tefillin first, you must put it on (if not for other considerations) because you took it with the intent of performing the mitzvah. That is why we arrange our tefillin carefully. However, you may intentionally take one out to place aside so you can take the other.
According to this view, you need not unzip your tefillin bag only halfway. Even if your hand ends up closer to the head-tefillin, you did not unzip the bad for the immediate purpose of removing the tefillin nearest your hand. Therefore, the rule against passing over a mitzvah does not apply.
IV. Passing Rooms
However, R. Cohen’s prooftext seems to run counter to this approach. The Mishnah Berurah (25:4) offers an uncharacteristic ruling without precedent on this subject. He writes that if someone intends to pray at home and passes the room in which his tefillin are stored, while his tallis is in a farther room, he must put on his tefillin immediately so as not to pass over this mitzvah. Apparently, the Mishnah Berurah does not limit the rule to only cases in which you are trying to perform the mitzvah. Even when you are walking by, you may not pass the mitzvah opportunity. (See also the language of the Arukh Ha-Shulchan above.) Therefore, R. Cohen ruled, when you unzip the tefillin bag completely, your hand is closer to the head-tefillin and due to other considerations you must pass over that mitzvah. It is better to unzip the bag only half-way to avoid the situation.
I am not issuing a ruling or condemning those who unzip their tefillin bags all the way. However, the change in technology brought about by the zipper seems to demand a renewed (if somewhat belated) look at this halakhah.