The custom of spending three months of the rainy season in a fixed place is a ritual successfully observed since the time of the Lord Buddha. In those day, however, villagers attributed young seedling damage at the start of the planting season to unnecessary travel by monks. Realizing that monks on pilgrimages could accidentally tread on young plants, the Lord Buddha decreed that his followers spend three months of the rainy season in permanent dwellings.
In cases of necessity, such as taking care of sick monks or parents or conducting religious functions, monks may travel and stay away from their monasteries during this period. However, they are required to return within seven days.