The Fast of Esther (, ) is a fast from dawn until dusk on Purim eve. This fast, unlike other fasts, is a custom. It is not mentioned in the Talmud, but only in the Midrash and later sources from the days of the Gaonim. Therefore it is considered less severe than the other fasts. Origin and purpose The fast commemorates one of two events in the Book of Esther: either Esther and the Jewish community of Shushan having fasted for 3 days and 3 nights before she approached the king (), or a fast which is presumed to have occurred on the 13th of Adar, when the Jews fought a battle against their enemies. It is a common misconception that this fast dates to the time of Esther. states "They had established for themselves and their descendants the matters of the fasts and their cry", but this refers instead to the fasts mentioned in . The first mention of the fast of Esther is as a minhag that is referenced in the Gaonic period. A 2010 study examines the origin of the fast and the reason for its arising in the Gaonic period. Laws The fast is observed on the 13th day of the Hebrew month of Adar. (When the year has two Adar months, it is observed only in the second Adar). If the date of the Fast of Esther falls on Shabbat (Saturday), the fast is instead observed on the preceding Thursday, as this was the case in 2004, 2007, 2010, 2011, 2013, 2014, and 2017. This will occur again in 2024. (Shulchan Aruch S.686 s.2) As the fast of Esther is not one of the four public fasts ordained by the Prophets, the laws concerning its observance are more lenient; pregnant women, nursing mothers, and those who are weak are not required to observe it. Fasting in the Book of Esther It is generally accepted in the rabbinic tradition that the original three-day "Fast of Esther" mentioned in chapter 4 of Book of Esther occurred on the 14th, 15th, and 16th days of Nisan, these being the eve and first two days of Passover. While halacha normally forbids fasting on Passover, it is believed that Esther reasoned it would be better to fast on one Pesach lest they all be destroyed and thus never be able to observe the holiday in the future. But due to