大毘盧遮那成佛經疏 9.66

9.66

右句義中，伽伽那是虛空義，娑摩是等義，阿娑摩是無等義，所謂等虛空無等也。如來法身，本性淨故、無分別故、無邊際故，等同虛空。然復有無量無邊不思議功德，非彼虛空所能譬喻，故云無等也。復次阿娑摩是不等義，不等者所謂二乘。今既等同虛空，又等此無等，故云等虛空無等也。以最初伽子為真言體，眾生界中來去亦不可得，法界中來去相亦不可得，以如來如去不可得，故名為大空。以此大空性淨之水，用浴無垢之身，是為閼伽真實之義也。

In the meaning of the phrases above: gagana means space; sama means equal; asama means unequalled; that is to say, 'equal to space, unequalled.' Because the Tathāgata's dharmakāya is fundamentally pure by nature, non-conceptual, and boundless, it is equal to space. Yet it also possesses immeasurable, boundless, and inconceivable virtues that cannot be exemplified by space; hence it is called 'unequalled.' Furthermore, asama means unequal, and the 'unequal' refers to the two vehicles. Now, being equal to space, it is also equal to this unequal; thus it is said to be 'equal to space, unequalled.' Taking the initial syllable ga as the essence of the mantra: within the realm of sentient beings coming and going are ungraspable, and within the dharmadhātu the marks of coming and going are also ungraspable; because tathāgata ('thus-come') and tathāgata ('thus-gone') are ungraspable, it is called the great emptiness. Using this water that is pure in its great empty nature to bathe the immaculate body—this is the true meaning of argha.