Māgha Pūjā, Makha Bucha (Thai: มาฆบูชา) is one of the important Buddhist festivals celebrated on the full moon day of Māgha in Cambodia, Laos, Myanmar and Thailand, and usually falls in the middle of February. The purpose of the festival is to aim spiritual merits such as not to commit any kind of sins; do only good; purify one’s mind. Māgha Pūjā is a public holiday in Cambodia, Laos, Myanmar, and Thailand and is an occasion when Buddhists tend to go to the temple to perform merit-making activities.
The third lunar month is known in the Thai language as Makha (Pali: Māgha); Bucha is also a Thai word (Pali: Pūjā), meaning “to venerate” or “to honor”. As such, Makha Bucha Day is for the veneration of Buddha and his teachings on the full moon day of the third lunar month.
Originally, Māgha Pūjā day marks the four auspicious occasions occurring at the Veḷuvana bamboo grove, near Rājagaha in northern India ten months after the enlightenment of the Buddha. On that occasion, as recorded in the commentary to the Mahāsamayasutta, DN-Comm 20) four marvelous events occurred:
1,250 disciples came to see the Buddha that evening without being summoned.
All of them were Arahants, Enlightened Ones, and all were ordained by the Buddha himself.
The Buddha gave those Arahants the principles of Buddhism, called “The ovadapatimokha”. Those principles are: To cease from all evil; To do what is good; To cleanse one’s mind. In Thailand, this teaching has been dubbed the “heart of Buddhism”.
It was the full-moon day.
On the evening of Makha Bucha full moon day in Thailand,
each temple holds a candlelight procession called a wian thian (wian meaning to circle around; thian meaning candle). Holding flowers, incense and a lighted candle, the monks and congregation members circumambulate clockwise three times around the phra ubosot (ordination hall), once for each of the Three Jewels: the Buddha, the Dharma, and the Sangha.
tham bun: Making merit by going to temples for special observances and join in the other Buddhist activities.
rap sin’: Keeping the Five Precepts. Practice of renunciation: Observe the Eight Precepts, practice of meditation and mental discipline, stay in the temple, wearing white robes, for a number of days.
(Credit to Wikipedia, Magha Puja)