大乘義章 1.109

1.109

問曰：何故眾生空者說為空行，不名無我？釋言：眾生着我之中，有十六種，所謂我、人、眾生、壽命、養育、知、見，如是一切。若說空行，通攝十六我人等空，故名空行；若言無我，不攝餘空，為是不論。

Question: Why is the emptiness of sentient beings spoken of as the practice of emptiness and not called selflessness? Explanation: Among the clingings to a self by sentient beings, there are sixteen kinds: namely, the self, the person, the sentient being, the life-span, the nourisher, the knower, the seer, and all such [conceptions]. If one speaks of the practice of emptiness, it comprehensively subsumes the emptiness of all sixteen—the self, person, and so on—and is therefore called the practice of emptiness; if one were to say selflessness, it would not subsume the remaining types of emptiness, which is why it is not discussed [in that way].