This sugya discusses the common scenario in which one is Halachically exempt from performing all other Mitzvos because he is currently engaged in the performance of a mitzvah.  The source of this principle is derived from the words “Beshivtecha Bevaisecha Uvelechtecha Vaderech”.  Chazal explain that the reason these words are written in the singular (rather than the plural) form is to imply that the obligation to recite the Shema is only while one is involved in his own pursuits.  However, one who is involved in a Mitzvah (Osek b’mitzva) is exempt.  Hence, the general rule of “Ha’osek B’mitzvah Patur Min Hamitzvah”.

There are many forms of performing Mitzvos (some more active and some more passive) and many types of Mitzvos (Min Hatorah, Mid’rabanan, Safek Mitzvah, etc.).  This Sugya analyzes these various types and how this exemption applies to each.  The classic example described in the Gemara is of one who is guarding a lost object and is therefore exempt from performing other Mitzvos.  By way of example, if someone approached him for Tzedakah at that time, he would not be obligated to give.

The question then arises, how “involved” would one need to be in the performance of a Mitzvah so that he would be exempt from all others?  As in the example above, if one is simply storing a lost item in his home (hashavas aveidah), does that exempt him from all other Mitzvos?  Or would he need to be actively doing something to protect that item at that time?  If one is wearing a Tallis or Tefillin in Shul, does that exempt him from the Mitzvah of Tzedakah?  Or is one only exempt when the performance of the second Mitzvah would compromise his performance of the first one?  This question is the subject of a debate amongst the Rishonim, and this Sugya analyzes this debate and the resulting Halacha lma’aseh.

Some of the questions discussed:

• ·         Is the reason for the exemption because one cannot concentrate on two things at once, or is it a general exemption?
• ·         What if it’s possible to do both?
• ·         If one did stop performing one Mitzvah to do another Mitzvah, is he yotzeh the second Mitzvah?  For example, if an Onen said Shema, is he yotzeh?
• ·         Is a Sofer writing Tefillin (which is a Mitzvah Kiyumis but not a chiyuv) pattur from other Mitzvos?
• ·         If a Kohen is in the middle of davening, must he stop to Duchen?
• ·         Is a Tzedakah collector obligated to daven?
• ·         If one is doing the Mitzvah Nichum Aveilim and sof zeman Krias Shema is approaching, is he patur or should he stop and recite Shema?
• ·         Is one exempt from a Mitzvah Min Hatorah if he is busy performing a Mitzvah Mid’rabanan?
• ·         If one is attending a wedding, is he mechuyav in the Mitzvah of Tzedakah?
• ·         If one is attending a Chupah – should he leave to daven Minchah if sh’kia is approaching?