大方廣佛華嚴經搜玄分齊通智方軌 2.23

2.23

First, explaining the name: That which is supreme and pure among practices is called brahmacaryā. In essential terms, brahmacaryā has two aspects: retributive result and upāya. Initial cultivation is 'pure'; final completion is 'brahma'. In terms of retributive result, the desire-realm heavens are 'pure', and the form-realm heavens are 'brahma'. In terms of benefit for oneself and benefit for others, benefit for oneself is 'pure', and benefit for others is 'brahma'. Hence the Nirvāṇa-sūtra says: 'The three trainings are the supreme noble practice; the four immeasurables are the brahma [practice].'