佛祖統紀 33.38

33.38

盂蘭盆供　經言。是佛弟子修孝順者。應念念中常憶父母乃至七世父母。年年七月十五日以百味飲食安盂蘭盆中。施佛及僧。以報父母長養慈愛之恩（盂蘭盆經○此翻解倒懸。言奉盆供於三寶福田。用以解饑虛倒懸之急）。

The Ullambana Offering: The scripture says that disciples of the Buddha who cultivate filial piety should, in thought after thought, constantly remember their parents, and even their parents of seven lifetimes. Every year on the fifteenth day of the seventh month, they should place delicacies of a hundred flavors in the ullambana bowl and offer them to the Buddha and the Saṅgha, so as to repay their parents' grace of nurturing and compassionate love (Ullambana-sūtra: This translates as 'rescuing from hanging upside down'; it means offering the bowl to the field of merit of the Three Jewels to relieve the emergency of hunger and being hung upside down).