The Buddha’s deliverance of the first sermon—the Dhammacakkappavattana Sutta—is known as the Dhamma Day. Gotama Buddha gave the Discourse on the Turning of the Wheel of the Dhamma on the full moon of Äsala (July) in the Deer Park, Sarnath, India.

On the full moon day, higher ordained Buddhist monks commence observing the ‘Rain Retreat’ (vassāna) for three months by committing themselves to remain in one place. They use the three months to teach the Dhamma to their lay devotees and strive to deepen their understanding of the Dhamma and its practice by developing wisdom and compassion. It is a widespread tradition that Buddhist devotees make a formal invitation to the members of the saṅgha (monastic community) by requesting them and pledging to provide the Four Requisites throughout this period of spiritual and religious observance.