大毘盧遮那成佛經疏 10.72

10.72

次豪相真言者，此是如來無量功德之所成就以為莊嚴。此是功德之聚，故作三昧女形也。是釋迦眷屬，亦入寶處三昧而說此真言耳。

Next is the mantra of the ūrṇā: this is accomplished through the immeasurable merit of the Tathāgata as an adornment. Because it is a mass of merit, it assumes the form of a samādhi maiden. As a member of Śākyamuni's retinue, she also enters the Ratnasambhava samādhi and speaks this mantra.