大毘盧遮那成佛經疏 17.26

17.26

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.