The Vap Full Moon Poya is a very significant Poya in the Buddhist calendar.
According to Buddhist history, many events related to the life of the Buddha occurred on this Poya day.
It was on a Vap Full Moon Poya day that the Buddha ended his seventh (Vassana) retreat for the rainy season since his enlightenment which he had spent in the celestial abode of Tavatissa.
There he had engaged in preaching Abhidhamma to the devas and deities headed by Matrudeva.
Accompanied by a procession of devotees, the Buddha descended near the city gates of Sankassapura, whereupon having preached Dhamma to the great crowds which flocked to witness the strange event, he declared Arahat Sariputta as the most intelligent person among all the disciples, when he successfully answered various difficult questions put to him by the Buddha.
During the ancient era, Vap was known as the period of sowing.