分別功德論 1.12

1.12

As for the Buddha being incomprehensible: formerly, when the Buddha was in a quiet chamber, Brahmā devas as numerous as the sands of the Ganges came to the Buddha's place, wishing to know what samādhi the Buddha was in, yet they could not know which meditative absorption or samādhi he was in. Secret matters of ṛddhi transformations like this cannot be comprehended even by the two vehicles, how much less by ordinary mortals.