Maudgalyayana was foremost in supernatural powers among the Buddha's disciples. While his mother was alive, she slandered the sages and those who were virtuous; therefore, she fell into the realm of the hungry ghosts after death. Using his supernatural powers, Maudgalyayana learned of his mother's suffering and wished to offer her food. Even though she was hungry, whenever food entered her mouth, it turned into ashes. Maudgalyayana sought the Buddha's advice on how to save his mother. The Buddha told him that her negative karma was so strong that individual effort was insufficient to rescue her. Maudgalyayana was instructed to offer a variety of food to the Sangha on the last day of the rainy season retreat. The merits gained from the offerings could help her repent her wrongdoings and free her from suffering. This was the origin of the Ullambana service.