大毘盧遮那成佛經疏 13.102

13.102

次觀音印。初作開剖合掌，以空指地指聚而相捻，餘六指散之，其火風指皆並相著，水指獨立，即是也。

Next is the mudrā of Avalokiteśvara. First form the opened-lotus añjali, gather the space [thumb] and earth [little] fingers together to pinch each other, and disperse the remaining six fingers; the fire [middle] and wind [index] fingers are joined side by side, and the water [ring] finger stands independently—this is it.