大毘盧遮那成佛經疏 13.201

13.201

次左手作拳，舒風指火指，以空指壓地水指，甲為刀鞘。其右手亦如是作之為刀，內刀鞘中。即不動尊印也。其鞘手仰，刀手覆也。降三世印。如五股金剛（更問）。

Next, make a fist with the left hand, extend the wind finger and fire finger, and press the earth and water nails with the space finger to make a scabbard. The right hand also does this to make a sword, inserting it into the scabbard. This is the Acalanātha mudrā. The scabbard hand is palm-up, and the sword hand is palm-down. The Trailokyavijaya mudrā is like the five-pronged vajra (inquire further).