大毘盧遮那成佛經疏 17.18

17.18

As for the eighth mudrā, having joined the palms (the palms facing each other), first turn to the left (when turning, the right hand is face down and the left face up, joined as before), then turn to the right (when turning, the left is face down and the right face up, remaining joined without separating)—this is it. This is the Tathāgata's swift retention mudrā, meaning the Tathāgata's power of secret supernatural penetration, the meaning of holding with swift power. The maṇḍala is like space as before, but changed to a blue color, surrounded by numerous white dots. The mantra is: This is the syllable khi; adding the samādhi [dot], it is the bīja. yoga mahāyoga: meaning the yoga of the buddhas. mahāyogini (2): this mantra lord abides in the great yoga; to those who have not attained yoga, it causes them to attain it. It means being able to bestow wishes upon practitioners, granting them mastery in yoga. yogeśvari (3) khaṃ (level tone): space. jale: arising, meaning born from space. ka is doing, making these arisings and so on in space. ke (4) svāhā.