Nyūbutsu samaya is not the name of an abstract doctrine. It is a concrete mantra that appears in the kanjō of the Mahāvairocana Sūtra.

In the Mahāvairocana Sūtra, Mahāvairocana rises from deep meditation and expounds this "mantra of entering the Buddha's samaya" (nyūbutsu sammaya jimyō). Jimyō means a mantra, a vidyā. Though it is a word voiced aloud, layered within it are the equality in which buddha and beings are not separated, the fundamental vow by which the Buddha never abandons us, the working that removes delusion, and the working that rouses us from sleep.

The Commentary on the Mahāvairocana Sūtra reads each single syllable of the transliterated words as "a gate for entering the Dharma-realm." It is not enough to replace the words with an explanatory paraphrase. In the kanjō, the voice chanting the mantra, the mudrā formed with both hands, and the mind that visualizes the disciple as the Buddha's own body are layered together as a single act. Therein lies the way a mantra is, in esoteric Buddhism.

To introduce here where the mantra is found in the texts is not the same as authorizing the reader to practice it. The practice of nyūbutsu samaya, including how it is recited, is cultivated after receiving transmission from an ācārya. It is not something to be done in one's own fashion on the basis of an article alone.

The spellings 三摩耶 (samaya) and 三昧耶 (sammaya) differ only in their Chinese characters; both transliterate the Sanskrit word samaya. In its headings, this article uses the form 三摩耶.

"Entering the Buddha" is not moving somewhere else. It is the fixing of the direction of one's relation to the Buddha.

The Mahāvairocana Sūtra teaches that the child of the Buddha who hears this mantra "does not transgress or overstep in any dharma." This is not a guarantee that one's conduct thereafter will automatically be right, or that one will never stray again. Through the kanjō, the Buddha's vow becomes the ground on which one stands; the words describe that religious direction. Precisely because people still stray and may turn their backs on the vow, the precepts and repentance are taught.

The Commentary on the Mahāvairocana Sūtra expresses this turning as "entering the Buddha's precept of equality and being entrusted to the sacred womb." The sacred womb (seitai) is a metaphor for being enfolded and nurtured within the Buddha's life. One does not approach the Buddha by one's own strength alone; one entrusts oneself to the vow the Buddha has already held out. That is what "entering" means here.

Samaya is not a mere promise. The Commentary on the Mahāvairocana Sūtra shows, in four words, how the Buddha's vow works.

Nyūbutsu samaya appears at the moment in the kanjō (abhiṣeka) when the ācārya forms the mudrā, seals the disciple's crown with it, and recites the mantra.

The scene the Commentary on the Mahāvairocana Sūtra depicts is this: the ācārya visualizes the disciple's body as the body of Mahāvairocana, and first seals the crown with the mudrā of entering the Buddha's samaya. Then other mudrās are impressed at the heart and at the navel. The disciple is not treated as a being still far from the Buddha; the disciple is welcomed into the kanjō as one equal to the Buddha's own body.

The body forming the mudrā, the voice chanting the mantra, the mind visualizing the disciple as the Buddha's body — these three are not separate. That is why nyūbutsu samaya is not knowledge completed by reading an explanation, but an event handed from master to disciple.

Beyond nyūbutsu samaya lie the samaya precepts (sanmaya-kai): precepts for living in answer to the Buddha's vow.

The Mahāvairocana Sūtra lists four roots. Not to abandon the true Dharma. Not to abandon the aspiration for awakening (bodhicitta). Not to begrudge the teaching that suits the other person. Not to abandon the practice of benefiting all living beings. What is asked is not only what one is forbidden to do, but what one must never let go of.

In his Catalogue of Newly Imported Sūtras (Go-shōrai mokuroku), Kūkai recorded that the ācārya Huiguo (Keika Ajari) first conferred on him the precepts of arousing the aspiration for awakening, and only afterward permitted him to enter the kanjō hall. Before the esoteric methods, one receives the heart that walks in the same direction as the Buddha. Here one can see why the samaya precepts are made the foundation of the kanjō.

Nyūbutsu samaya is the word for the side that enters the vow. It is possible that a person may later turn against that vow. That is otsu-samaya (samayatikrama): stepping over the vow one has tied. And yet the relationship tied at the entrance does not become meaningless. For the person who realizes they have turned against it, the path of repentance and renewal is also taught.

The way the samaya precepts are organized is expressed differently among schools and ritual lineages, but the core lies in not separating the Buddha's fundamental vow from one's own aspiration for awakening.

Among the mantras connected with samaya there is also "oṃ samayas tvaṃ" (on sanmaya satoban). It is a different mantra from the mantra of entering the Buddha's samaya.

"Oṃ samayas tvaṃ" appears in the kanjō of the Vajraśekhara Sūtra lineage, a mantra that declares to the disciple, "You are the samaya." The mantra of entering the Buddha's samaya that we have followed in this article, by contrast, appears in the Mahāvairocana Sūtra and opens the meanings of equality, the fundamental vow, the removal of obstacles, and rousing and awakening. The words and the sources are different.

And yet the two resonate in that neither leaves the disciple outside the Buddha's vow. One shows the entering of the Buddha's samaya; the other declares to the disciple, "You are the samaya." Without blending the similar names into one, we receive each in the place of the kanjō where it is set.

The procedure of nyūbutsu samaya is received within transmission. But its heart need not be left behind deep within the temple.

When you wish to cultivate the mudrā, the mantra, and the contemplation, please receive the guidance of an ācārya. Hearing the mantra at a temple, chanting the daily service shown by the temple, and performing a practice conferred in the kanjō are not the same thing. When in doubt, the sure path is to ask the temple to which you belong.

What can be carried back into daily life is the heart that seeks to answer the Buddha's fundamental vow. Prayer does not end where one's wishes are granted by the Buddha. Not treating the single person before you carelessly. Not letting go of the true teaching. Not abandoning the good of others that you can do. When you lay your own step upon the Buddha's vow, nyūbutsu samaya ceases to be a word from a distant kanjō.