Pchum Bun is a Cambodian 15-day religious festival, culminating in celebrations on the 15th day of the tenth month in the Khmer calendar, at the end of the Buddhist Lent, Vassa. In 2023, Pchum Bun will begin on October 13 and end on October 16.

The day is a time when many Cambodians pay their respects to deceased relatives of up to seven generations. Buddhist monks chant the suttas in Pali language overnight (continuously, without sleeping) in prelude to the gates of hell opening, an event that is presumed to occur once a year, and is linked to the cosmology of King Yama. During this period, the gates of hell are opened and spirits of the ancestors are presumed to be especially active. In order to liberate them, food-offerings are made to benefit them, some of them having the opportunity to end their period of purgation, whereas others are imagined to leave hell temporarily, to then return to endure more suffering; without much explanation, relatives who are not in hell (who are in heaven or other realms of existence) are also generally expected to benefit from the ceremonies.