首楞嚴義疏注經 7.25

7.25

諸佛菩薩不食此食，為令福增示現而食，令修行者福慧具足，速得圓滿。如佛受純陀最後供養，令其具足檀波羅蜜。此亦如是，故須供養。

The buddhas and bodhisattvas do not consume this food; in order to cause merit to increase, they appear to consume it, enabling practitioners to be endowed with merit and wisdom and swiftly attain perfection. Just as the Buddha accepted Cunda's final offering to enable him to complete the dāna-pāramitā, this is likewise so; therefore, offerings must be made.