八識規矩補註 2.46

2.46

此識至佛果位，轉成上品無漏淨體，號無垢識，與相應大圓鏡智同發起時，普照十方圓明法界也。契經云：「如來無垢識，是淨無漏界，解脫一切障，圓鏡智相應。」通揀四智，謂平等性智、妙觀察智各有三品，見道下品，修道中品，究竟上品，故因中轉也；大圓鏡智、成所作智各唯上品，故於果中轉也。故頌云：「六七二識因中轉，前五第八果中圓。」

When this consciousness reaches the stage of the Buddha-fruit, it is transformed into a supreme undefiled pure essence, termed the immaculate consciousness; when it arises simultaneously with the corresponding great round mirror wisdom, it universally illuminates the perfect, radiant Dharma realm of the ten directions. The sūtra states: "The Tathāgata's immaculate consciousness / is the pure undefiled realm, / liberated from all obstacles, / associated with the round mirror wisdom." Universally distinguishing the four wisdoms: equality wisdom and marvelous observation wisdom each have three grades: inferior on the path of seeing, middling on the path of cultivation, and supreme at the ultimate; therefore they are transformed in the causal stage. The great round mirror wisdom and the duty-fulfillment wisdom are each only of the supreme grade; therefore they are transformed in the fruit. Thus the verse states: "The sixth and seventh consciousnesses are transformed in the causal stage; / the first five and the eighth are perfected in the fruit."