大方廣佛華嚴經搜玄分齊通智方軌 2.23

2.23

一釋名者。行中上淨，故名梵行也。要論梵有二，謂報及方便。始修為淨，成就為梵。若據報者，欲天為淨，色天為梵。若約自利利他，自利為淨，利他為梵。故《涅槃經》云「三學為勝聖行，四無量為梵」也。

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].'