We are fortunate today to have the great Gaon Rabbi Shemuel Pinchasi from Israel deliver the Daily Halacha. The audio clip contains Rav Pinchasi’s oration which was in Hebrew. The explanation appears below.
The Mechilta (Halachic work on the Book of Shemot from the Tanna'im), commenting on the verse, "No work shall be performed on them [Yom Tov]" (Shemot 12:16), writes, "It shall not performed by a gentile." The Mechilta thus understood this verse to mean that the Torah forbids a Jew from not only performing Melacha (forbidden activity) on Shabbat or Yom Tov, but even asking a gentile to perform Melacha on his behalf on Shabbat or Yom Tov.
On the basis of this comment in the Mechilta, the Sefer Yerei'im (by Rabbi Eliezer of Metz, France, 1115-1198) and the Semag ("Sefer Mitzvot Gadol" by Rabbi Moshe of Couchy, France-Spain, 13th century) ruled that Amira Le'nochri – asking a gentile to perform Melacha on one's behalf on Shabbat – constitutes a Torah prohibition. Other Rishonim, however, including Tosafot, Rashi and the Rambam, maintain that this prohibition was enacted by the Sages, and this is the accepted position.
Different explanations have been offered as to why the Rabbis enacted this prohibition of Amira La'nochri. Rashi, both in Masechet Shabbat and in Masechet Avoda Zara, suggests two reasons. First, he explains this prohibition on the basis of Shelichut (literally, "agency"), the notion that an action performed on behalf of another can be attributed to that other person. Hence, when a gentile performs a Melacha on Shabbat at a Jew's behest, Halacha considers the Jew to have performed the Melacha. (Although generally speaking a gentile cannot act as a Shaliach – an agent – for a Jew in the Halachic sense, on the level of Rabbinic enactment a gentile can act as a Shaliach when this would yield a stringency.) Secondly, Rashi suggests that instructing a gentile on Shabbat to perform a Melacha on one's behalf violates the law of "Ve'daber Davar" (based on Yeshayahu 58:13), which forbids speaking in weekday matters on Shabbat. When a Jew asks a gentile to perform a Melacha, he in essence speaks about forbidden activity, in violation of "Ve'daber Davar."
The Rambam posits yet a third explanation, claiming that if Jews would be allowed to ask gentiles to perform Melacha on their behalf on Shabbat, they would eventually begin taking the Shabbat prohibitions lightly. Ultimately, this would result in Jews themselves performing Melacha on Shabbat, and the Rabbis therefore found it necessary to forbid Amira Le'nochri.
These different approaches to the reason underlying the prohibition of Amira Le'nochri yield practical Halachic ramifications. According to Rashi's first explanation, that the Sages forbade asking a gentile to perform Melacha because the action would then be attributed to the Jew, it would make no difference when the Jew requested that the gentile perform the given act. It would thus be forbidden to ask a gentile even early in the week to perform a Melacha on one's behalf on Shabbat, since the action the gentile performs will be seen as the Jew's action.
According to Rashi's second understanding, however, that Amira Le'nochri is forbidden by virtue of the prohibition against speaking of weekday matters on Shabbat, this prohibition would apply only on Shabbat itself. Since this approach focuses on the speech, rather than the action performed, it would restrict the prohibition to instructions given to a gentile on Shabbat itself.
By the same token, Rashi's second approach would yield a more stringent ruling regarding an instruction given to a gentile on Shabbat to perform a Melacha after Shabbat. If the issue at hand is speaking mundane matters on Shabbat, then it would be forbidden to ask a gentile on Shabbat to perform a Melacha even after Shabbat. According to Rashi's first approach, however, that the prohibition stems from the concept of Shelichut, the prohibition applies only to actions performed by a gentile on Shabbat.
Many Poskim (Halachic authorities), including Rabbi Yaakov Emden (Germany, 1697-1776), the Chida (Rabbi Chayim Yosef David Azulai, Israel, 1724-1806) and the work "Erech Ha'shulchan," ruled that Halacha accepts the stringent conclusions of both approaches. Hence, it is forbidden to ask a gentile even before Shabbat to perform a Melacha on one's behalf on Shabbat, and it is likewise forbidden to ask a gentile on Shabbat to perform Melacha on his behalf at some point after Shabbat.
The Shulchan Aruch (307:5) rules that for purposes of a Mitzva, one may ask a gentile to perform on Shabbat an activity classified as a "Shevut," meaning, that is forbidden only by force of Rabbinic enactment (as opposed to Torah law). For example, if a Shofar was caught in a tree on Rosh Hashanah, it would be permissible to ask a gentile to climb the tree and retrieve the Shofar so that one could fulfill the Mitzva of Shofar blowing on Rosh Hashanah. Since climbing trees is forbidden on Shabbat and Yom Tov only on the level of Rabbinic enactment, one may – for the purpose of a Mitzva – ask a gentile to perform this act on Shabbat or Yom Tov. The Shulchan Aruch here disagrees with the view of Tosafot, who held that this provision applies only for purposes involving the Mitzva of Berit Mila (circumcision), but not for other Mitzvot.
Summary: One may not instruct a gentile to perform Melacha (forbidden activity) on his behalf on Shabbat. This applies even to instructing a gentile before Shabbat to perform Melacha on his behalf on Shabbat, as well as instructing a gentile on Shabbat to perform a Melacha on his behalf after Shabbat. For the purposes of facilitating the performance of a Mitzva, one may ask a gentile to perform an action forbidden on Shabbat only on the level of Rabbinic enactment.
