Khao Phansaa , marks the beginning of "Buddhist Lent."   According to legend, there was once a group of six monks walking about during the rainy season.   They were careless about where they put their feet, stepping on frogs and crushing new rice plants.   This angered the farmers who complained to the Buddha.   The Buddha made the rule for the sangha, the community of monks, to observe Khao Phansaa , which means "entering the rainy season."

The rule is that for three months during the rainy season the monks must vow not to stay overnight away from their temple, unless they have permission for special circumstances such as visiting sick parents, going to deliver sermons.   In any case, they can never be gone more than seven days.

On the full-moon day of the eighth lunar month people go to the temple with incense sticks, candles, and pha ab nam fon (a yellow robe for bathing) and offer them to the Buddha statue in the temple.   After that, they perform the prayer/chanting ceremony, vow to follow the precepts (five rules of conduct), and listen to a sermon.

On the first day of the waning moon, lay people tak baat (give offerings) , take the precepts, and listen to a sermon.   After the evening prayers, the novices and monks make their vows to stay in their wat and kuti , residence, for the three rainy months.