Asalha Puja 1st moon of Āsādha

Asalha Puja, also known as Dhamma Day, is one of the most important holidays in Theravada Buddhism, celebrating as it does the Buddha's first sermon, the "Sermon in the Deer Park" at Sarnath, in which he expounded to his five former associates the doctrine which had come to him after his enlightenment. This pivotal first sermon, often called "setting the wheel of dhamma in motion," is the teaching that is summarized for Buddhists in the Four Noble Truths:

there is suffering (dukkha); suffering is caused by desire (tanha); there is a state (nibbana) beyond suffering and greed; and finally, the path to nirvana is through the eightfold path. All the different schools and traditions of Buddhism revolve around the central doctrine of the Four Noble Truths.

This first sermon is not only the first structured speech given by the Buddha after his enlightenment, it also contains the essence of all his subsequent teaching. At the end of the talk, one of the five participants recounted his understanding of what had been said and requested to be received as a disciple, a request which the Buddha granted, thus establishing the first order of monks .

The day is observed by making offerings at temples and listening to sermons. The next day is known in Thailand as Thai: วันเข้าพรรษา Wan Khao Phansa; it is the first day of Thai: พรรษา vassa, the Theravada rains retreat.