Phra Sangkajjai (Pāḷi: Mahākaccāyana Thera) was previously known as Kaccāna – an adept and popular teacher of Dhamma. People regarded Mahākaccāyana as a very attractive, good-looking young man. His features in physical appearance were highly similar to that of the Buddha. Mahākaccāyana was well aware of the fact that people often tend to mistake his appearance for that of the Buddha. Thus, he wished to distinguish himself from the looks of the Buddha, upon which he decided transform himself into a fat and ugly monk.
In one of his past lives, at the time of Buddha Padumuttara (the 13th Buddha), Mahākaccāyana had made a vow to become a great teacher of theDhamma. From that moment on he performed countless meritorious deeds throughout his future lives. Through the immense accumulation of merit he had inherited strong magical powers. One of those many offerings he made contained a brick of gold he offered to the cetiya (Pāḷi; Sanskrit: stupa) of the Kassapa Buddha (the 27th Buddha), which lead to his future rebirth in which he was born with a body radiating a golden hue.
Mahākaccāyana always presented many generous gifts to his followers, which lead to the rise of Mahākaccāyana’s popularity among the laity. In this way, Mahākaccāyana became an important object of a cult wherein his saintly charisma became manifest in a popular image (monk with a fat belly) which represents material wealth and prosperity. This particular image is worshipped by laypeople, for they believe Mahākaccāyana Thera is a fully enlightened monk who is worthy of worship. Moreover, Mahākaccāyana is also seen as an arahant fulfilling peoples’ wishes.
Apart from worship for good fortune, Mahākaccāyana Thera is also venerated for lending his worshippers assistance in cultivating the path of practice. Moreover, he instructs the laity to make merit and to practice right (verbal, physical, mental) speech and action.