Seudah shlishit (Hebrew: סעודה שלישית, romanized: səʿuḏah šəlišiṯ third meal) or shaleshudes (Yiddish, an elided form of Hebrew: שָׁלֹשׁ סְעֻדוֹת, romanized: šāloš sǝʿuḏot, lit.
16:25, in which the word for day, hayom, appears three times with reference to the manna that fell in a double portion on Friday.
In some Hasidic circles, this third meal continues hours after the Sabbath has officially ended concluding with Birkat HaMazon over the same cup with Havdalah giving rise to the tradition of Melaveh Malkah.
Special Sabbath songs that are often sung at this meal include Bnei Heichala (a Kabbalistic hymn by Rabbi Isaac Luria), Mizmor L'David (23rd Psalm), and Yedid Nefesh (a piyyut, or liturgical poem, composed by 16th century Kabbalist rabbi Elazar ben Moshe Azikri).
Some rabbinic commentators conjecture that this three meal requirement was instituted in order to lend a special measure of honor to Shabbat, since the normative practice at the time was to eat two meals in the course of a normal weekday: one during the day and one at night.
In commemoration of the double portion of manna that fell for Shabbat, it is customary to have two loaves of bread at each meal.