大毘盧遮那成佛經疏 13.96

13.96

次慈氏印。作三補吒，而屈二風指，令指頭至火指根下，二空指並而壓之，餘如常。此印如窣都波形者，以持一切如來法身塔故，猶如觀音持佛身也。真言歸命如前。

Next is the mudrā of Maitreya. Form the saṃpuṭa, bend the two wind [index] fingers so that the fingertips reach beneath the roots of the fire [middle] fingers, place the two space [thumbs] side by side to press them, and the rest is as usual. This mudrā is shaped like a stūpa because he upholds the dharmakāya stūpa of all tathāgatas, just as Avalokiteśvara upholds the Buddha's body. The mantra homage is as before.