大毘盧遮那成佛經疏 17.26

17.26

第三月在火輪中，謂三角赤漫荼羅，住勝上火輪也。觀在其中，以其囉字為身也。作慧刀印，謂三補吒合掌，屈二風捻二空也。其出入息赤色。三月義如前，謂三月三十日三千日等，以見為限也。此三月中不求一切食，謂不得乞食等。若有施來者，得隨意食之；無人施與則不食，但以囉字為食耳。以此方便，燒一切罪障令無有餘也。以此義故，一切暗盡明成，謂佛慧明也。備，謂備具用此印也。

In the third month, one is in the fire circle, which means a triangular red maṇḍala, abiding in the superior fire circle. One visualizes being within it, taking the syllable RA as one's body. Form the wisdom sword mudrā, which is a saṃpuṭa añjali with both wind fingers bent to touch the two space fingers. The in-and-out breath is red. The meaning of the three months is as before, whether three months, thirty days, three thousand days, and so forth, taking seeing as the limit. During these three months, one does not seek any food, meaning one must not beg for food and the like. If there are offerings brought, one may eat at will; if no one offers food, one does not eat, taking only the syllable RA as nourishment. By this upāya, all sins and hindrances are burned away without remainder. For this reason, all darkness is exhausted and illumination is accomplished, which refers to the light of the Buddha's wisdom. 'Equipped' means fully using this mudrā.