Riddle Of The Day

RIDDLE This תענית ציבור is being held on 2 different days of the year depending on which country you live in.  ANSWER The מגן אברהם תק"פ quotes The תניא רבתי  “ On Friday Parshas חקת, Yechidim (individuals) fast. That day, 20 [24] wagons of seforim were burnt. The fast day was established for Friday חקת rather than the 9th of Tamuz, because they made a שאילת חלום if the גזירה was מן השמים. The answer came back,  of זאת חקת התורה the Targum  writes "דא גזירת אורייתא” This is a גזירה from Shomayim and fasting should be done on Fridays of Parshas חקת. When the 2nd-day שבועות falls on Shabbos (like this year) Parshas חקת is read in Eretz Yisroel a week earlier than in Chutz Laaretz Hence the תענית is one week earlier in E, Yisroel than in Chutz Laaretz R. Zev Rivkin Shlita asked, "If someone is in E.Y. the first Parshas חקת and will be in Chu"l for the second Parshas חקת, does he fast a) the first Friday, b)the second Friday c) or both?". answers appreciated