Ketubot 104a:2

Death is a concept discussed throughout Jewish literature, beginning with the second chapter of the Torah, in the context of the world's creation. Sources throughout the generations grapple with the concept of mortality, responding emotionally to death, and the laws and customs that surround death and mourning.

There are assorted fast days scattered across the Jewish calendar. During the two major fast days, Yom Kippur and Tisha B'Av, one abstains from food, drink, washing, and sexual relations for 25 hours. During the other, minor fast days, one abstains from food and drink from sunup to sundown.