Halakhah su Genesi 31:16

Responding in the following issue of Mevakshei Torah, Rabbi Diskin, a rosh yeshivah at Yeshivat Kol Torah and the author of Mas'at ha-Melekh on the Rambam's Mishneh Torah, cogently distinguishes between the two situations. For the resident of the Diaspora the second day of Yom Tov is a day on which forbidden forms of labor may not be performed. Hence any labor performed on that person's behalf was performed on a day that, for that individual, is Yom Tov. The recipient of a fax on Shabbat sent from a locale where it is not Shabbat derives benefit from an act performed in a place in which it is not Shabbat for anyone. For all persons, Shabbat is determined by the beginning and end of the seventh day at a particular latitude and longitude.¹⁰See Seforno, Genesis 31:16; R. David ibn Zimra, Teshuvot Radvaz, I, no. 76; R. Israel Lipschutz, Tiferet Yisra’el, Berakhot, note appended to Bo‘az, end of chap. 1; and R. Joseph Saul Nathanson, Teshuvot Sho’el u-Meshiv, Mahadura Revi’ah, no. 154. There are no restrictions upon acts performed at that locale when it is not Shabbat in that place. Shabbat at any place on the globe is determined by local time even for a person who is not physically present in that locale.¹¹See Teshuvot Ereẓ Ẓevi, no. 44, who permits a person standing on the side of the halakhic dateline on which it is Shabbat to direct a person standing on the other side of the dateline to perform an act of labor prohibited on the Sabbath.