大毘盧遮那成佛經疏 17.24

17.24

Furthermore, as stated above, the realization of reality as of a single flavor is difficult to believe and difficult to understand. The Tathāgata, by means of other upāyas consisting of worldly methods of recitation, assists this realization of reality; therefore he next expounds the method of six months of recitation. Yet these are all secret and ultimate, not different from what preceded. In the first month, one should visualize a vajra: it is a square maṇḍala, yellow in color. One visualizes one's own body seated within it, identifying one's body with the syllable A. The syllable A is square and yellow; one should make it fill the interior of the body completely without deficiency, so that the entire body is this syllable. One should form the five-pronged vajra mudrā without needing to hold a rosary. For this mudrā, make a hollow-palmed añjali, bend both water [ring] fingers and clasp them right over left inside the palms, extend both space [thumb] fingers together, and bend the two wind [index] fingers toward the backs of the middle fingers—this is the Vajrapāṇi mudrā. During this one month, consume only milk and eat no other food. Simply visualize the recited mantra emerging from the navel and entering through the nose, just like regulating the breath. At that time, visualize this mantra as the breath itself, its color also yellow. If visualizing the mantra, let each phrase be one breath. If visualizing the bīja syllable, simply breathe continuously. Although it is called one month, whether it takes ten, a hundred, or up to a lakṣa of months, the limit must be seeing. Furthermore, 'one' has the meaning of a single characteristic and a single flavor; seeing this is called completing one month.