Ksitigarbha Sutra was first translated from Sanskrit into Chinese in the 7th century A.D., T'ang Dynasty by Venerable Tripiṭaka Master Shikshananda of Khotan in Central Asia. Speaking the Dharma for the sake of his mother, Lady Maya, this Sutra was spoken by Sakyamuni Buddha towards the end of his life to the beings of the Trayastrimsha Heaven as a mark of gratitude and remembrance for his beloved mother.
This is also known in Buddhism as the filial piety sutra. It tells the story of Earth Store - (the literal translation of the Bodhisattva's name in Sanskrit) Boddhisattva's vows. How in past lives as a filial daughter of a Brahmin woman she saved her mother from Hell by making offerings and cultivation. Later she vowed to save all beings from suffering and is now the Earth Store Bodhisattva.
Another importance of the Great Vows of Earth Store Bodhisattva, the Ksitigarbha Sutra is on the teaching of filial piety. Filial piety is the first step in morality. That is why this Sutra is so important for all Buddhist beginners. It not only relate to the relationship between oneself and one's parents but also as a universal code of duty for all living beings. It is an initial step toward embodying one's universal duty, one begins with duty to one's immediate family and friends, of which parents are foremost in importance.
This Sutra describes the past lives of Bodhisattva Ksitigarbha, his great vow made to that effect by him and the benefit accruing from that vow.
The vow is that "if the hell is not yet empty, I vow not to become a Buddha."
Chapter VIII. Appreciation of Emperor Yama & His Followers — The ruler of Yamadevaloka & Judge of the Dead