Asalha or the Dhamma Day celebrates the first teaching of the Buddha which He delievered to a group of five friends. Asalha or Dhamma Day is a significant Buddhist festival that celebrates the Buddha's first sermon, known as the Dhammacakkappavattana Sutta, which he gave to his disciples after attaining enlightenment. The day also marks the beginning of the three months long Rains retreat during which monks remain confined to their monasteries and focus on their meditation. The day is celebrated on the full moon of the eighth lunar month of Asalha which usually falls in July according to the Gregorian calendar. 

The sermon laid out the Four Noble Truths and the Eightfold Path, which are the foundation of Buddhist teachings. It is an important day for Buddhists to reflect on the teachings of the Buddha and to renew their commitment to the path of spiritual growth and liberation. On this day, Buddhists typically visit temples and monasteries to offer prayers, light candles, and make offerings of flowers and incense. They may also participate in meditation and other spiritual practices, and listen to teachings on the Buddha's life and teachings.