菩薩瓔珞本業經 1.54

1.54

「復次十觀心所觀法者，一、二諦正直。所謂學習第一義諦，觀一切法相如，不可得故。以慈悲喜捨教授六天人，剃頭被三寶衣，出家菩薩共一切僧，佛法無二故、第一清淨故。

"Furthermore, regarding the phenomena contemplated by the ten minds of contemplation: first is the uprightness of the two truths, that is to say, learning the ultimate truth and contemplating that all marks of phenomena are such and cannot be apprehended. With loving-kindness, compassion, sympathetic joy, and equanimity, one instructs the devas and humans of the six [heavens of desire], shaves the head, dons the robes of the three jewels, and as a home-leaving bodhisattva joins together with the whole Saṅgha, because the Buddha-Dharma is non-dual and supremely pure.