佛說盂蘭盆經 1.9

1.9

The Buddha told the good sons and good daughters: "Disciples of the Buddha who cultivate filial piety should, in thought after thought, constantly remember their parents, making offerings even to parents of seven past lives. Every year on the fifteenth day of the seventh month, always with filial piety, compassion, and remembrance for the parents who gave birth to them and even parents of seven past lives, they should prepare an ullambana basin to offer to the Buddha and the Saṅgha, so as to repay their parents' kindness for rearing and tenderly loving them. All disciples of the Buddha should uphold this practice."