大方廣圓覺修多羅了義經略疏 1.517

1.517

無邊際故。良由如來藏性本自如斯，豈須減舊添新、滅惑生智？是以三重泯絕，冥合覺心，將此為本修行，始得正名因地。

Because it has no boundaries. This is truly because the nature of the tathāgatagarbha is fundamentally like this; how could it require decreasing the old and adding the new, destroying delusion and producing wisdom? Therefore, with the triple cessation, one mysteriously accords with the enlightened mind; taking this as the basis for cultivation, one only then properly gains the name of 'causal stage.'