長阿含經 15.p121

15.p121

“Thus, wanderer, as a result of these events, those ascetics and priests say that losing mindfulness is the source of sentient beings. Only a Buddha thus knows it, and he knows what’s beyond it. He knows it, but he isn’t attached to it. He truly knows suffering and its formation, cessation, enjoyment, danger, and escape. He’s called ‘Tathāgata’ because he was liberated without remainder by his equal observation.”