大毘盧遮那成佛經疏 13.73

13.73

次如來普光印。二空指並而屈入掌中，二風指直竪（各不相着，皆直竪之），二火指頭相合，稍闊其節如鈴鐸形，餘指同前，即是也。真言曰：歸命如前。

Next is the Tathāgata's Universal Radiance Seal. Place the two space fingers side by side and bend them into the palms; the two wind fingers stand straight up (not touching each other, both erect); the two fire fingertips meet, with their joints slightly widened like the shape of a bell; the remaining fingers are as before; that is it. The mantra says: Homage is as before.