The Fast of Esther (Ta'anit Ester, Hebrew: תַּעֲנִית אֶסְתֵּר) is a fast on Purim eve commemorating two communal fasts undertaken by the Persian Jewish community of Shushan in the Book of Esther, for the purpose of praying for salvation from annihilation by an evil decree which had been instigated by the royal vizier, an anti-jewish enemy, of the Amalekite nation.

This fast, unlike other fasts, is a custom. It is not mentioned in the Talmud; however it is mentioned in the Midrash and other later sources from the days of the Gaonim. Therefore it is considered less severe than the other fasts.^[1]

Esther asked Mordechai to have the Jews fast and pray on her behalf for 3 days and 3 nights, before she approached her husband, king Ahasuerus to beg for the life of her people. Another is presumed to have occurred on the 13th of Adar, the day before the Jews fought a battle to defend against their enemies, who had been given an irrevocable permission to murder Jews for one day a year on the 14th of that month, which is now a Jewish holiday of Purim on account of their victory.^[2]

Before approaching the king unbidden at risk of her life Esther told Mordechai (Esther 4:16)

Go, gather together all the Jews that are present in Shushan, and fast ye for me, and neither eat nor drink three days, night or day; I also and my maidens will fast in like manner; and so will I go in unto the king, which is not according to the law; and if I perish, I perish.

The fast is from dawn to dusk.

It is a common misconception that this fast dates to the time of Esther. Esther 9:31 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 Zechariah 8:19.^[3]

The first mention of the fast of Esther is as a minhag that is referenced in the Gaonic period.^[4] A 2010 study examines the origin of the fast and the reason for its arising in the Gaonic period.^[5]

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, this was the case in 2004, 2007, 2010, 2011, 2013, 2014, 2017 and 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.^[6]

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.^[7] 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 the normal prohibition of fasting on Passover, the "Fast of Esther" instead became attached to the eve of Purim, the 13th of Adar.^[7]

The 13th of Adar itself was a fast day for the warriors while going out to battle, as it had been customary to fast during battle in order to gain divine favor. ^[8]

The Gregorian calendar dates correlated with 13 Adar, from dawn until nightfall, for 2021–2026 are:^[9][10]

• Fasting in Judaism
• Aneinu
• Selichot
• Haman (Bible)
• Amalek