大毘盧遮那經阿闍梨真實智品中阿闍梨住阿字觀門 1.11

1.11

If a practitioner acts as an *ācārya* for others, they must first establish the Great Compassion Garbhakośa King Maṇḍala and dwell in the Buddha-stage, assembling these syllables to form the body and thereby dwelling in the Buddha-stage. When distributing the syllables, they are divided into four tiers, and each tier has three kinds of refuge: the head is the first part; the throat is the second part; the heart is the third part; and the navel is the fourth part.