Regarding further the background of the ullambana, Maudgalyāyana was an unenlightened man who was unaware of his mother’s suffering in the realm of hungry spirits. As a child he received a non-Buddhist education in Brahmanism, mastering all the non-Buddhist scriptures such as the four Vedas and eighteen great sūtras, but he was still unable to see where his mother had gone after her death. Later, at the age of 13 Maudgalyāyana, together with Śāriputra, visited Śākyamuni Buddha and became His disciple. He became a sage of the initial rank by eliminating delusions of views, rose to the rank of arhat by overcoming delusions of thought, and gained the three or six kinds of supernatural powers.

With his heavenly eyes wide open, Maudgalyāyana could see everything throughout the triple thousand worlds as though they were all reflected in a spotless mirror. He was able to see everywhere in the great earth and in the three evil realms. It was as if he were looking at the fish below the water through the ice shining in the morning sun. It was then he saw his own mother in the realm of hungry spirits.

Without anything to eat or drink, his mother was emaciated, and her skin looked like a pheasant whose feathers were all plucked, and her bones were worn away to such an extent that they looked like lines of round stones. Her head without hair looked like a ball, her neck as thin as a thread, and her stomach swollen as large as the ocean. Her appearance, as she begged by opening her mouth wide and pressing her palms together, resembled a leech trying to catch the scent of human beings. How heartbreaking it was for Maudgalyāyana to see his own mother, suffering from hunger and wanting to cry at the sight of her own son in her previous life! It must have been sadness beyond description. …

Venerable Maudgalyāyana felt so sorry for his mother that he made use of his supernatural powers to send a meal to her. His mother gladly grabbed the meal with her right hand and put it into her mouth while covering it with the left hand. At this moment the meal somehow changed into fire, bursting into flames, as if wicks were put together to build a fire, causing the mother to get burned all over. Shocked at seeing this, Maudgalyāyana hurriedly used his supernatural powers again to pour plenty of water. The water, however, somehow changed to firewood, causing more burns to his mother. It was a dreadful scene!

Realizing that his own supernatural powers were not enough to save his own mother, Maudgalyāyana hurriedly went to see the Buddha and cried, “I was born in a non-Buddhist family, but became a disciple of the Buddha and ascended to the rank of arhatship, won freedom from the chain of life and death in the triple world, and gained the three or six supernatural powers of arhatship. However, when I tried to save my mother from the great suffering in the realm of hungry spirits, I only intensified her suffering. I am grief-stricken.” The Buddha replied to Maudgalyāyana, “Your mother’s sin is too serious for you alone to save her. No matter how many persons there are, the powers of such as heavenly beings, terrestrial gods, demons, non-Buddhists, Taoist priests, the Four Heavenly Kings, Indra, and the King of the Brahma Heaven cannot save her. You can only save your mother from suffering by gathering holy priests in all the worlds throughout the universe on the 15th of the 7th month, treat them with a feast.” As Maudgalyāyana held a feast according to the instructions of the Buddha, his mother was able to escape the kalpa (aeon) of suffering in the realm of hungry spirits. So, it is preached in the Ullambana Sūtra.

Stemming from this, people in the Latter Age of Degeneration after the passing of the Buddha hold the ullambana service every year on the 15th of the 7th month. Today this is a common practice held as an annual event.

Urabon Gosho, On theUllambana Service, Writings of Nichiren Shōnin, Faith and Practice, Volume 4, Page 172-173