大方廣佛華嚴經疏 51.25

51.25

第四善知識者，行起必依善友，故次明之。未知善令知、未識惡令識，故凡所順益皆我善友，故十皆益也。上云即得親近善知識是。

Fourth, virtuous friends: the arising of practice must rely on virtuous companions, hence it is explained next. Causing what is not yet known of goodness to be known, and what is not yet recognized of evil to be recognized, whatever accords and benefits is my virtuous friend, hence all ten are beneficial. This is what was referred to above as "namely obtaining closeness to virtuous friends."