菩薩瓔珞本業經 1.48

1.48

「佛子！七、為得四無礙故。所謂五善根：正觀、煗觀、頂觀、忍觀、三界空第一觀，能生十地無相大明慧故、聖人胎未變故、第一空平等故。

"Buddha-son! Seventh is to attain the four unhindered understandings, that is to say, the five wholesome roots: the contemplation of correct view, the contemplation of heat, the contemplation of summits, the contemplation of forbearance, and the supreme contemplation of the emptiness of the three realms, because they can generate the signless great luminous wisdom of the ten grounds, because the noble womb has not yet altered, and because the supreme emptiness is equal.