Nikini full moon day falling due one month after the commencement of “Wassana Kala“the rainy season: is of special significance for Buddhists due to a number of incidents that took place on this day.
Attainment of Arahatship by the Buddha’s chief attendant, Ananda Maha Thera, commencement of the first Dhamma Sangayana, convocation to settle the Buddhist canon and “Pasu Vas” or the commencement of the “Vas” period by those who had not started the period of sojourn on the Esala full moon day are some of them. For Sri Lankans this day is further more significant because of the world famous Kandy Esala Perahera which normally ends on this day.
The rainy season in Dambadiva-India begins during the month of Esala (July – August). It is extremely cold in the snowy peaks of Himalayas and in the valleys where ascetics meditate under the shade of trees.
Due to cold weather and heavy rain it is not convenient for them to sit under trees and meditate. Even birds build sheltered nests to live in during this season with birdies. Some of them even migrate to other countries where there is less rain. Buddhist monks also sojourn with house holders during this season
The “Pali” word “Vas” means the rains “Viseema” means dwelling. Therefore “Vas Viseema” means to sojourn during the rainy season. “Vassana Kala” or the rainy season of three months begins on Esala full moon day. Commencing the “Vas” period from Esala full moon day is called “Purmikawa” or “Pera Vas”. However the bhikkhus who could not commence the Vas period on Esala Full Moon day are allowed to start observing Vas on the Nikini Full Moon day. This is called “Pasuvas”.
Buddhist monks commence “Vas” on Nikini full moon day in keeping with the enactment called “Santhaha Karanaya” The circumstances which led to the enactment of “Santhaha Karanaya” was the hardships caused to the bhikkhus due to rain.
After the establishment of Buddhasasana bhikkus engaged in the propagation of Dhamma and meditation during all four seasons, spring, summer, autumn and winter regardless of adverse weather conditions specially during the rainy season. People were concerned about the hardships caused to bhikkus and pains taken by them which the people thought was “Attakilamathanuyogaya – giving extreme pains to the body or physical exertion. Some people went even to the extent of criticizing the extreme pains taken by bhikkhus. These criticisms reached the ears of King Bimbisara.
On a day before the Nikini full moon day King Bimbisara requested the Buddha to sojourn for the rainy season from Nikini full moon poya day in his kingdom, at Rajagaha Nuwara. The Buddha accepted this invitation.
‘Pasuvas’ or the custom of commencing the ‘Vas’ period from Nikini full moon day came into being in that manner. Thus bhikkus sojourn in ‘wassawasa” place of residing in the rainy season starting from Esala full moon day or Nikini full moon day.
It was on the Nikini Full Moon day three months after The Buddha’s “parinibbana” that the first Dharma sangayana-convocation was held to settle the Buddhist canon.
The immediate cause for conducting the first Dhamma Sangayana was the behaviour of a monk named Subaddha after the parinibbana of the Buddha.