The Halacha below was derived from multiple classes orated by Rabbi Eli Mansour in the Bekiim B'Halacha series. Click on any of the dates below to hear the original audio files, which are the sources for today's Halacha below. 04/01/25 ; 04/02/25 ; 04/10/25 ; 04/28/25 ; 05/12/25 Can One Fulfill the Misva by Wearing Only One Tefillin—Shel Yad or Shel Rosh? We know the Misva of Tefillin includes both the Shel Yad (the arm Tefillin) and the Shel Rosh (the head Tefillin). But what if someone can only wear one? Does he fulfill the Misva at all? What if a person is injured, or cannot afford both pieces? Can the two components of Tefillin function independently, or are they one inseparable Misva? Are the Arm and Head Tefillin Considered One Misva or Two? The Gemara in Menahot (36a) records a debate as to whether the Tefillin Shel Yad and the Tefillin Shel Rosh are one Misva or two separate Misvot. The Halacha follows the view that they are two distinct Misvot. The Rambam codifies this in Hilchot Tefillin (4:1), stating that each one has its own Beracha and its own independent status. Accordingly, if a person only wears the Shel Yad or only the Shel Rosh, he has indeed fulfilled a Misva. Ideally, one must wear both, but wearing just one still earns the reward of a Misva. What If One Can Only Afford One Tefillin? A person who cannot afford to buy both Tefillin should not delay until he can purchase both. Instead, he should immediately buy whichever one he can afford—Shel Yad or Shel Rosh—and wear it. The Ben Ish Hai writes explicitly that each part is a Misva in its own right. Waiting would mean losing out on daily Misvot. Similarly, Hacham Ovadia Yosef writes in Yehave Da'at (3:2) that there is no reason to postpone the Misva. If a person later acquires the second piece, he should start wearing both—but in the meantime, he must not miss the opportunity to fulfill what he can. Does It Matter Which One Is Worn First If You Only Have One? Ideally, the Tefillin Shel Yad is put on first, followed by the Shel Rosh. But if a person only has one of them—regardless of which—it should be worn without hesitation. The order only applies when both are available. In practice, some authorities say the Shel Yad is preferred if only one can be worn, since it comes first in the verse and is placed before the Shel Rosh. However, this is not an absolute rule. If a person has only the Shel Rosh available, he should wear it, make the proper Beracha, and fulfill that part of the Misva. What If a Person Is Injured and Cannot Use His Arm or Head? If a person injures his left arm and cannot wear the Shel Yad, he should still wear the Shel Rosh. Likewise, if he has a head injury or bandage that prevents the Shel Rosh from sitting properly, he should at least wear the Shel Yad. One should never skip Tefillin entirely just because he cannot wear both parts. The value of each is significant and independent. Summary - The Shel Yad and Shel Rosh are two separate Misvot. - One who wears only one of them fulfills a Misva. - If one can only afford or wear one, he should still do so without delay. - Ideally, the Shel Yad is worn first, but the order does not prevent one from fulfilling the Misva. - Injuries or limitations do not exempt a person from performing the part of the Misva he is able to do.