大毘盧遮那成佛經疏 13.29

13.29

此是真言之心也。此長阿字為行，傍二點為三昧。為令此法堅固故，故後有點也。然作拳法有其四種：第一如常作拳法，大指竪之，此是一也。次以空指在於掌中而拳之，名金剛拳，第二也。叉二手而合作拳，令十指出現於外，此名指在外拳，第三也（並右指加左）。次以十指相叉，皆令十指頭在於掌內，此名二手拳，第四也（亦右指加左上）。

This is the heart of the mantra. This long syllable *ā* is practice; the two dots at the side are samādhi. In order to make this dharma firm and stable, there is a dot behind. Now, there are four kinds of fist-making methods: First, making a fist as usual with the thumb erect—this is the first. Next, keeping the space finger inside the palm and forming a fist; this is called the vajra fist—the second. Interlocking both hands and joining them to make a fist, letting the ten fingers appear on the outside; this is named the fingers-on-the-outside fist—the third (with the right fingers placed over the left). Next, interlocking the ten fingers, causing all ten fingertips to be inside the palms; this is named the two-hands fist—the fourth (also with the right fingers placed over the left).