大乘起信論廣釋卷第三．四．五 4.71

4.71

[Treatise:] And up to being fully satisfied, [with nothing lacking, it is called the tathāgatagarbha, and also called] the Tathāgata's dharmakāya. [Commentary:] This establishes the names. Subsuming the extensive under the brief, it says "and up to". Showing that it is replete with all virtues, it says "fully satisfied". With no further thought, it says "with nothing lacking". Being able to subsume the myriad virtues of the Tathāgata on the fruit stage, and subsumed by the Tathāgata's cognition, it is called the "tathāgatagarbha". When the attributes of the fruit-virtues become manifest, they can give rise to the saṃbhoga[kāya] and nirmāṇa[kāya]; serving as the reliance for the myriad virtues, it is called the "dharmakāya". Therefore, "fully satisfied" and so forth are all [...] established designations, not separate meanings. Hence the new translation states: "Based on this meaning, it is called the dharmakāya and so forth".