Vassa also called Rains Retreat, is the traditional retreat during the rainy season lasting for three lunar months from July to October. During this time Buddhist monks remain in a single place, generally in their temples. In some monasteries, monks dedicate the Vassa to intensive meditation practice. During Vassa, many Buddhist lay people reinvigorate their spiritual training and adopt more ascetic practices, such as giving up meat, alcohol, or smoking (Vassa is sometimes known as "Buddhist Lent”). Commonly, the number of years a monk
has spent in monastic life is expressed by counting up the number of Vassas he has observed.
The origins of the Vassa tradition are ascribed to early Buddhist times. Gotama Buddha ordered his disciples to observe a pre-existing practice whereby holy men avoided travelling for a three month period during the rainy season, in order to avoid damaging crops. Asalha Puja or “Dhamma Day" commemorates the Buddha’s first sermon, Dhammacakkappavattana Sutta, given at the Deer Park in Benares to the First Five Disciples, advising Buddhists to practice the Middle Path, avoiding the 2 extremes of sensual indulgence and self-mortification, to realize the Four Noble Truths, namely, Suffering, Cause of Suffering, End of Suffering, and Middle Path to end suffering. This resulted in the founding of the Buddhist sangha, as Kondanna, one of those Five Disciples attained first level of enlightenment, that is a Sotapana, thus completed the Triple Gem of Buddha (the Teacher), Dharma (the teaching of the Truth), and Sangha (the Noble Disciples). The day is observed by donating offerings to temples and listening to sermons. The annual Rains retreat (vassa) begins the following day. The end of vassa is marked by joyous celebration. The following month, theKathina ceremony is held, during which the laity gathers to make formal offerings of robe cloth and other requisites to the Sangha.