大毘盧遮那成佛經疏 9.54

9.54

右句義中，摩訶妹呾𭌆也是大慈義，毘庾蘗帝是生義，所謂大慈生義也。以昧字為真言體，即是莾字加三昧畫，是故轉聲呼之。莾是心義我義，亦名大空。言此心蓮花，為妄我所纏不得增長，今自證知心實相故，從慈悲藏中八葉鬚蘂次第開敷，故曰從大慈生也。復次淨菩提心樹王種子，從慈悲地中滋長茷盛開萬德花，以方便故成實，故曰從大慈生也。當以字門廣釋之。

In the meaning of the phrase above: 'mahāmaitrī' means great loving-kindness; 'abhyudgate' means arising—that is, arising from great loving-kindness. It takes the syllable MAI as the substance of the mantra: that is, the syllable MA with the samādhi-stroke added, so its sound is transformed when recited. MA means mind, and means self, and is also called great emptiness. This means that the lotus flower of the mind, bound by the false self, could not grow; now, having personally realized the mind's dharmatā, its eight petals, stamens, and pistils bloom in succession from the storehouse of loving-kindness and compassion; hence it is said to 'arise from great loving-kindness.' Furthermore, the seed of the king of pure bodhicitta trees grows lushly from the soil of loving-kindness and compassion, blooming into the flowers of myriad virtues, and yields fruit through upāya; hence it is said to 'arise from great loving-kindness.' This should be extensively explained according to the syllable-gateways.