https://blog.naver.com/gytlr52/221509450459

Google autotranslate (see link above for the original Korean):
He practiced alone on Mount Tiantai in India and saw and realized the laws of the universe that operate without change, such as the rising and setting of the sun, the blooming and falling of leaves, the blooming of flowers in spring, and the bearing of fruit in fall. He acquired the powers of the Three Brightnesses (the Brightness of the Night, the Brightness of the Heavenly Eye, and the Brightness of Leakage) and of self-benefit and self-benefit of others. It is said that with these powers, he could bestow blessings on living beings and fulfill their wishes, and so he came to receive offerings from living beings. He is enshrined in the Dokseonggak (獨聖閣) of the temple.

He is also called Dokseongsu (獨聖修) or Dokseongjonja. Dokseong is a general term for saints in Theravada Buddhism who alone realized the principle of karma and attained the Way. However, Nabanjonja is called Dokseong because he alone achieved enlightenment.

There are several theories about its origin.

According to legend, he is a disciple of Buddha who appeared in the Dharma-ending Age and taught sentient beings, but he does not appear among the ten great disciples of Shakyamuni Buddha or the names of the 500 Arhats, and there is no record of his name or unique name as Nabanjonja in Buddhist scriptures, and faith in Nabanjonja did not arise in Chinese Buddhism either. Faith in Nabanjonja is a form of faith that can only be found in our country, and the Nabanjonja enshrined in our temples are depicted with white hair, very long eyebrows, and often smiling. Therefore, Choi Nam-seon of Yukdang understood that the Nabanjonja enshrined in the Samseonggak (三聖閣) or Dokseonggak (獨聖閣) of temples was not a Buddhist god, but a unique Korean god who arose from the Dangun faith.

In ancient times, Dangun was worshipped as the founder of the nation, and it is said that Dangun later entered the mountain and became a mountain god, or a god of immortality, so Dangun was worshipped as a mountain god or a god of immortality. Therefore, shrines were built on famous mountains and the mountain god or god of immortality was worshipped. However, when Buddhism was introduced, a shrine was built in a quiet place above the main temple building and the mountain god and god of immortality were worshipped together, and the Chilseong (seven stars) that came from China were also worshipped together. This is because the statue of Nabanjonja is understood as the statue of Dangun. However, this too is unreasonable. The first Dokseonggak was built in Korea in 1693 (19th year of King Sukjong’s reign), and since it was only built in earnest in temples in the 1800s, it is not considered to have been incorporated and worshiped during the period when Buddhism was introduced.

In Buddhism, Nabanjonja is regarded as a field of blessings in the last days and is believed to be one of the Arhats who can bestow blessings. Therefore, according to another theory, he is regarded as Bindulojonja, one of the 16 Arhats . This is because he has many similarities in appearance, such as white hair and white eyebrows, and is also said to have similar supernatural powers.

It is said that Nabanjonja appeared in the Dharma-ending Age, bestowed blessings on living beings, eliminated disasters, and granted wishes before the coming of Maitreya Buddha. In temples, many solitary prayers are offered, because the venerable one’s supernatural powers are so great that those who make offerings and pray will quickly receive supernatural powers. This can be easily understood from the verse in the hymn recited when offering the solitary prayers, which states that Nabanjonja’s supernatural powers are rare in the world and that he can act, hide, and change at will.

It is known among the people that when making offerings to a saint with great spiritual powers, or a very strict and fearful personality, one must properly prepare offerings as well as bathing and purification. However, since Nabanjonja is a raw being, maji is not offered, but raw rice is offered. Nabanjonja is enshrined in Dokseonggak or Samseonggak of a temple, and a statue or painting of Nabanjonja is enshrined alone in Dokseonggak, while in Samseonggak, it is enshrined together with the Chilseong and Sansin.
[출처] 나반존자(那畔尊者)|작성자 천석