MN 121 Culasunnata Sutta: The Shorter Discourse on Voidness
Thus have i heard.
On one occasion the Blessed One was living at Savatthi in the Eastern Park, in the Palace of Migara's Mother. Then, when it was evening, the venerable Ananda rose from meditation, went to the Blessed One, and after paying homage to him, he sat down at one side and said to the Blessed One:"Venerable sir, on one occasion the Blessed One was living in the Sakyan country at a town of the Sakyans named Nagaraka. There, venerable sir, I heard and learned this from the Blessed One's own lips: 'Now, Ananda, I often abide in voidness.' Did I hear that correctly, venerable sir, did I learn that correctly, attend to that correctly, remember that correctly?"
Buddha: "Certainly, Ananda, you heard that correctly, learned that correctly, attended to that correctly, remembered that correctly. As formerly, Ananda, so now too I often abide in voidness. Ananda, just as this Palace of Migara's Mother is void of elephants, cattle, horses, and mares, void of gold and silver, void of the assembly of men and women, and there is present only this non-voidness, namely, the singleness dependent on the Sangha of bhikkhus; so too, a bhikkhu - not attending to the perception of village, not attending to the perception of people attends to the singleness dependent on the perception of forest."
"His mind enters into that perception of forest and acquires confidence, steadiness, and decision. He understands thus: 'Whatever disturbances there might be dependent on the perception of village, those are not present here; whatever disturbances there might be dependent on the perception of people, those are not present here. There is present only this amount of disturbance, namely, the singleness dependent on the perception of forest.' He understands: 'This field of perception is void of the perception of village; this field of perception is void of the perception of people. There is present only this non-voidness, namely, the singleness dependent on the perception of forest.' Thus he regards it as void of what is not there, but as to what remains there he understands that which is present thus: 'This is present.' Thus, Ananda, this is his genuine, undistorted, pure descent into voidness. "
"Again, Ananda, a bhikkhu - not attending to the perception of people, not attending to the perception of forest - attends to the singleness dependent on the perception of earth. His mind enters into that perception of earth and acquires confidence, steadiness, and decision. His mind enters into that perception of earth and acquires confidence, steadiness, and decision. He understands thus: 'Whatever disturbances there might be dependent on the perception of people, those are not present here; whatever disturbances there might be dependent on the perception of forest, those are not present here. There is present only this amount of disturbance, namely, the singleness dependent on the perception of earth.'"
" He understands: 'This field of perception is void of the perception of- people; this field of perception is void of the perception of forest. There is present only this non-voidness, namely, the singleness dependent on the perception of earth.' Thus he regards it as void of what is not there, but as to what remains there he understands that which is present thus: 'This is present.' Thus, Ananda, this too is his genuine, undistorted, pure descent into voidness."
"Again, Ananda, a bhikkhu - not attending to the perception of forest, not attending to the perception of earth - attends to the singleness dependent on the perception of the base of infinite space. His mind enters into that perception of the base of infinite space and acquires confidence, steadiness, and decision. He understands thus: 'Whatever disturbances there might be dependent on the perception of forest, those are not present here; whatever disturbances there might be dependent on the perception of earth, those are not present here. There is present only this amount of disturbance, namely, the singleness dependent on the perception of the base of infinite space.' " "He understands: 'This field of perception is void of the perception of forest; this field of perception is void of the perception of earth. There is present only this non-voidness, namely, the singleness dependent on the perception of the base of infinite space.' Thus he regards it as void of what is not there, but as to what remains there he understands that which is present thus: 'This is present.' Thus, Ananda, this too is his genuine, undistorted, pure descent into voidness. "
"Again, Ananda, a bhikkhu - not attending to the perception of earth, not attending to the perception of the base of infinite space - attends to the singleness dependent on the perception of the base of infinite consciousness. His mind enters into that perception of the base of infinite consciousness and acquires confidence, steadiness, and decision. He understands thus: 'Whatever disturbances there might be dependent on the perception of earth, those are not present here; whatever disturbances there might be dependent on the perception of the base of infinite space, those are not present here. There is present only this amount of disturbance, namely, the singleness dependent on the perception of the base of infinite consciousness.'"
" He understands: 'This field of perception is void of the perception of earth; this field of perception is void of the perception of the base of infinite space. There is present only this non-voidness, namely, the singleness dependent on the perception of the base of infinite consciousness.' Thus he regards it as void of what is not there, but as to what remains there he understands that which is present thus: 'This is present.' Thus, Ananda, this too is his genuine, undistorted, pure descent into voidness."
"Again, Ananda, a bhikkhu - not attending to the perception of the base of infinite space, not attending to the perception of the base of infinite consciousness - attends to the singleness dependent on the perception of the base of nothingness. His mind enters into that perception of the base of nothingness and acquires confidence, steadiness, and decision. He understands thus: 'Whatever disturbances there might be dependent on the perception of the base of infinite space, those are not present here; whatever disturbances there might be dependent on the perception of the base of infinite consciousness, those are not present here. There is present only this amount of disturbance, namely, the singleness dependent on the perception of the base of nothingness.' He understands: 'This field of perception is void of the perception of the base of infinite space; this field of perception is void of the perception of the base of infinite consciousness. There is present only this non-voidness, namely, the singleness dependent on the perception of the base of nothingness.' Thus he regards it as void of what is not there, but as to what remains there he understands that which is present thus: 'This is present.' Thus, Ananda, this too is his genuine, un-distorted, pure descent into voidness."
"Again, Ananda, a bhikkhu - not attending to the perception of the base of infinite consciousness, not attending to the perception of the base of nothingness - attends to the singleness dependent on the perception of the base of neither-perception-nor-non-perception. His mind enters into that perception of the base of neither-perception-nor-non-perception and acquires confidence, steadiness, and decision. He understands thus: 'Whatever disturbances there might be dependent on the perception of the base of infinite consciousness, those are not present here; whatever disturbances there might be dependent on the perception of the base of nothingness, those are not present here. There is present only this amount of disturbance, namely, the singleness dependent on the perception of the base of neither perception-nor-non-perception.' "
"He understands: 'This field of perception is void of the perception of the base of infinite consciousness; this field of perception is void of the perception of the base of nothingness. There is present only this non-voidness, namely, the singleness dependent on the perception of the base of neither-perception-nor-non-perception.' Thus he regards it as void of what is not there, but as to what remains there he understands that which is present thus: 'This is present.' Thus, Ananda, this too is his genuine, un-distorted, pure descent into voidness."
"Again, Ananda, a bhikkhu - not attending to the perception of the base of nothingness, not attending to the perception of the base of neither-perception-nor-non-perception - attends to the singleness dependent on the signless concentration of mind. His mind enters into that signless concentration of mind and acquires confidence, steadiness, and decision. He understand thus: 'Whatever disturbances there might be dependent on the perception of the base of nothingness, those are not present here; whatever disturbances there might be dependent on the perception of the base of neither-perception-nor-non-perception, those are not present here. There is present only this amount of disturbance, namely, that connected with the six bases that are dependent on this body and conditioned by life.' "
"He understands: 'This field of perception is void of the perception of the base of nothingness; this field of perception is void of the perception of the base of neither-perception-nor-non-perception. There is present only this non-voidness, namely, that connected with the six bases that are dependent on this body and conditioned by life.' Thus he regards it as void of what is not there, but as to what remains there he understands that which is present thus: 'This is present.' Thus, Ananda, this too is his genuine, undistorted, pure descent into voidness. "
"Again, Ananda, a bhikkhu - not attending to the perception of the base of nothingness, not attending to the perception of the base of neither-perception-nor-non-perception - attends to the singleness dependent on the signless concentration of mind. His mind enters into that signless concentration of mind and acquires confidence, steadiness, and decision. He understands thus: 'This signless concentration of mind is conditioned and volitionally produced. But whatever is conditioned and volitionally produced is impermanent, subject to cessation.'"
"When he knows and sees thus, his mind is liberated from the taint of sensual desire, from the taint of being, and from the taint of ignorance. When it is liberated there comes the knowledge: 'It is liberated.' He understands: 'Birth is destroyed, the holy life has been lived, what had to be done has been done, there is no more coming to any state of being.' "
"He understands thus: 'Whatever disturbances there might be dependent on the taint of sensual desire, those are not present here; whatever disturbances there might be dependent on the taint of being, those are not present here; whatever disturbances there might be dependent on the taint of ignorance, those are not present here. There is present only this amount of disturbance, namely, that connected with the six bases that are dependent on this body and conditioned by life.' He understands: 'This field of perception is void of the taint of sensual desire; this field of perception is void of the taint of being; this field of perception is void of the taint of ignorance. There is present only this non-voidness, namely, that connected with the six bases that are dependent on this body and conditioned by life.' Thus he regards it as void of what is not there, but as to what remains there he understands that which is present thus: 'This is present.' "
Thus, Ananda, this is his genuine, undistorted, pure descent into voidness, supreme and unsurpassed. "Ananda, whatever recluses and brahmins in the past entered upon and abided in pure, supreme, unsurpassed voidness, all entered upon and abided in this same pure, supreme, unsurpassed voidness. Whatever recluses and brahmins in the future will enter upon and abide in pure, supreme, unsurpassed voidness, all will enter upon and abide in this same pure, supreme, unsurpassed voidness. Whatever recluses and brahmins in the present enter upon and abide in pure, supreme, unsurpassed voidness, all enter upon and abide in this same pure, supreme, unsurpassed voidness. Therefore, Ananda, you should train thus: 'We will enter upon and abide in pure, supreme, unsurpassed voidness.'"
That is what the Blessed One said. The venerable Ananda was satisfied and delighted in the Blessed One's words.
In summary, the Buddha instructs Ananda on the "genuine, undistorted, pure descent into voidness" and how to reach an undisturbed state empty of lust, hate and delusion.
It covers practical issues on the attempt to develop an internal meditative dwelling of emptiness, to maintain it, and to see it through to Awakening- final knowledge and deliverance. Some of the issues include the need for conducive secluded place, types of conversation and thinking that are beneficial and harmful for the practice, the dangers of being distracted by visitors, and the proper attitude to have toward one's teacher.
References: 1. www.accesstoinsight.org 2. https://suttacentral.net/ 3. The middle length discourses of the Buddha (Bhikkhu Bodhi)