The most famous is the Platform Sutra that advocates for "sudden
enlightenment" that is a hallmark of Chan teachings. Just look at how
Huineng begins:
'The Great Master told the assembly, "Good friends, bodhi is fundamentally pure in its self-nature. You must simply use this mind [that you already have], and you will achieve buddhahood directly and completely. Good friends, listen well! This is the story of how I practiced and attained the Dharma."'
(Platform Sutra, ch 1, BDK ed, p 17)
Then throughout the scripture he explains the sudden teaching.
'To use wisdom to contemplate all the dharmas without grasping or rejecting is to see the nature and accomplish the enlightenment of buddhahood.'
(ch 2, p 31)
'Transcending delusion and transcending enlightenment, one should always generate prajñā. Eradicating the true and eradicating the false, one sees the buddha-nature. This is to accomplishthe enlightenment of buddhahood upon hearing these words.'
(ch 6, p 49)
The central method of Chan, translated here as nonthought, is itself equated with buddhahood:
'Good friends, to be enlightened to the Dharma of nonthought is for the myriad dharmas to be completely penetrated. To be enlightened to the Dharma of nonthought is to see the realms of [all] the buddhas. To be enlightened to the Dharma of nonthought is to arrive at the stage of buddhahood.'
(ch 2, p 34)
And to be clear, it talks not only of sudden enlightenment, but also sudden cultivation:
'The self-nature is without error, without stupidity, and without disruption. In moment after moment of thought, prajñā illuminates, constantly transcending the characteristics of dharmas. Independent and autonomous, he apprehends everything—how could there be any positing? The self-nature becomes enlightened itself, sudden enlightenment and sudden cultivation. There is no gradual progression. Therefore, one does not posit all the dharmas. The dharmas are quiescent—how could there be a progression?'
(ch 8, p 75)
On that point, here's Buswell's summary from the introduction of Bird in Flight Leaves no Trace:
'The answer of both Subul Sunim and Huangbo is deceptively simple: just stop thinking there is something we need to practice. Then the enlightenment inherent to the mind manifests itself naturally, and we spontaneously receive the transmission of the mind-dharma. In this way, religious practice is perfected through, and simultaneously with, enlightenment itself. This is the quintessential “sudden awakening accompanied by sudden cultivation” (Chinese dunwu dunxiu, Korean dono donsu 頓悟頓修) approach that has inspired Seon practice throughout much of its history.'
A bit more from Buswell (and Lopez) on the topic of sudden enlightenment: Slow-Motion Satori.
In Huangbo's words:
'Trainees who wish to achieve Buddhahood [should understand that] it is completely useless to study any of the Buddhist teachings — just study nonseeking and nonattachment. Nonseeking is for the mind (i.e., moments of thought) not to be generated, and nonattachment is for the mind not to be extinguished. Neither generating nor extinguishing—this is Buddhahood. The eighty-four thousand teachings are directed at the eighty-four thousand afflictions and are only ways to convert and entice [sentient beings into true religious practice]. Fundamentally all the teachings are nonexistent; transcendence is the Dharma, and those who understand transcendence are Buddhas. By simply transcending all the afflictions, there is no dharma that can be attained.'
(Essentials of the Transmission of Mind, ch 4, in Zen Texts, BDK ed, p 20)
Further on the path of sudden enlightenment, this one from Huangbo's teacher Baizhang Huaihai:
'Question: What is the essential method for sudden enlightenment in the great vehicle?
The master said,
You all should first put an end to all involvements and lay to rest all concerns; do not remember or recollect anything at all, whether good or bad, mundane or transcendental - do not engage in thoughts. Let go of body and mind, set them free.
With mind like wood or stone, not explaining anything with the mouth, mind not going anywhere, then the mind ground becomes like space, wherein the sun of wisdom naturally appears. It is as though the clouds had opened and the sun emerged.
Just put an end to all fettering connections, and feelings of greed, hatred, craving, defilement and purity all come to an end. Unmoved in the face of the five desires and eight influences, not choked up by seeing, hearing, discerning or knowing, not confused by anything, naturally endowed with all virtues and the inconceivable use of all paranormal powers, this is someone who is free.
In the presence of all things in the environment, to have a mind neither still nor disturbed, neither concentrated nor distracted, passing through all sound and form without lingering or obstruction, is called being a wayfarer.
Not setting in motion good, evil, right or wrong, not clinging to a single thing, not rejecting a single thing, is called being a member of the great vehicle.
Not bound by any good or evil, emptiness or existence, defilement or purity, doing or nondoing, mundane or transcendental, virtue or knowledge, is called enlightened wisdom. Once affirmation and negation, like and dislike, approval and disapproval, all various opinions and feelings come to an end and cannot bind you, then you are free wherever you may be; this is called a bodhisattva at the moment of inspiration immediately ascending to the stage of Buddhahood.'
(Sayings and Doings of Pai-Chang, p 78)
And from Baizhang's Dharma-brother Dazhu Huihai:
'Sudden Enlightenment means liberation during this lifetime. Just as a lion-cub, from the moment it is born, is a real lion, likewise anyone who practices the Sudden-Enlightenment method has, from the moment he begins his practice, already entered the Buddha-Stage. Just as the bamboo-shoots growing in springtime are not different from the parent bamboo-shoots, because they are also empty inside, likewise anyone who practices the Sudden-Enlightenment method to rid himself suddenly of false thought abandons, like the Buddhas, the sense of an ego and a personality forever. Being absolutely deep, still and void, he is, then, without an iota of difference, equal to the Buddhas.'
(Treatise On Entering The Tao of Sudden Enlightenment)
See more from two modern Chan teachers:
Enlightenment and Buddhahood by Sheng-yen
Gradual Cultivation and Sudden Enlightenment by Wei Chueh
'The Great Master told the assembly, "Good friends, bodhi is fundamentally pure in its self-nature. You must simply use this mind [that you already have], and you will achieve buddhahood directly and completely. Good friends, listen well! This is the story of how I practiced and attained the Dharma."'
(Platform Sutra, ch 1, BDK ed, p 17)
Then throughout the scripture he explains the sudden teaching.
'To use wisdom to contemplate all the dharmas without grasping or rejecting is to see the nature and accomplish the enlightenment of buddhahood.'
(ch 2, p 31)
'Transcending delusion and transcending enlightenment, one should always generate prajñā. Eradicating the true and eradicating the false, one sees the buddha-nature. This is to accomplishthe enlightenment of buddhahood upon hearing these words.'
(ch 6, p 49)
The central method of Chan, translated here as nonthought, is itself equated with buddhahood:
'Good friends, to be enlightened to the Dharma of nonthought is for the myriad dharmas to be completely penetrated. To be enlightened to the Dharma of nonthought is to see the realms of [all] the buddhas. To be enlightened to the Dharma of nonthought is to arrive at the stage of buddhahood.'
(ch 2, p 34)
And to be clear, it talks not only of sudden enlightenment, but also sudden cultivation:
'The self-nature is without error, without stupidity, and without disruption. In moment after moment of thought, prajñā illuminates, constantly transcending the characteristics of dharmas. Independent and autonomous, he apprehends everything—how could there be any positing? The self-nature becomes enlightened itself, sudden enlightenment and sudden cultivation. There is no gradual progression. Therefore, one does not posit all the dharmas. The dharmas are quiescent—how could there be a progression?'
(ch 8, p 75)
On that point, here's Buswell's summary from the introduction of Bird in Flight Leaves no Trace:
'The answer of both Subul Sunim and Huangbo is deceptively simple: just stop thinking there is something we need to practice. Then the enlightenment inherent to the mind manifests itself naturally, and we spontaneously receive the transmission of the mind-dharma. In this way, religious practice is perfected through, and simultaneously with, enlightenment itself. This is the quintessential “sudden awakening accompanied by sudden cultivation” (Chinese dunwu dunxiu, Korean dono donsu 頓悟頓修) approach that has inspired Seon practice throughout much of its history.'
A bit more from Buswell (and Lopez) on the topic of sudden enlightenment: Slow-Motion Satori.
In Huangbo's words:
'Trainees who wish to achieve Buddhahood [should understand that] it is completely useless to study any of the Buddhist teachings — just study nonseeking and nonattachment. Nonseeking is for the mind (i.e., moments of thought) not to be generated, and nonattachment is for the mind not to be extinguished. Neither generating nor extinguishing—this is Buddhahood. The eighty-four thousand teachings are directed at the eighty-four thousand afflictions and are only ways to convert and entice [sentient beings into true religious practice]. Fundamentally all the teachings are nonexistent; transcendence is the Dharma, and those who understand transcendence are Buddhas. By simply transcending all the afflictions, there is no dharma that can be attained.'
(Essentials of the Transmission of Mind, ch 4, in Zen Texts, BDK ed, p 20)
Further on the path of sudden enlightenment, this one from Huangbo's teacher Baizhang Huaihai:
'Question: What is the essential method for sudden enlightenment in the great vehicle?
The master said,
You all should first put an end to all involvements and lay to rest all concerns; do not remember or recollect anything at all, whether good or bad, mundane or transcendental - do not engage in thoughts. Let go of body and mind, set them free.
With mind like wood or stone, not explaining anything with the mouth, mind not going anywhere, then the mind ground becomes like space, wherein the sun of wisdom naturally appears. It is as though the clouds had opened and the sun emerged.
Just put an end to all fettering connections, and feelings of greed, hatred, craving, defilement and purity all come to an end. Unmoved in the face of the five desires and eight influences, not choked up by seeing, hearing, discerning or knowing, not confused by anything, naturally endowed with all virtues and the inconceivable use of all paranormal powers, this is someone who is free.
In the presence of all things in the environment, to have a mind neither still nor disturbed, neither concentrated nor distracted, passing through all sound and form without lingering or obstruction, is called being a wayfarer.
Not setting in motion good, evil, right or wrong, not clinging to a single thing, not rejecting a single thing, is called being a member of the great vehicle.
Not bound by any good or evil, emptiness or existence, defilement or purity, doing or nondoing, mundane or transcendental, virtue or knowledge, is called enlightened wisdom. Once affirmation and negation, like and dislike, approval and disapproval, all various opinions and feelings come to an end and cannot bind you, then you are free wherever you may be; this is called a bodhisattva at the moment of inspiration immediately ascending to the stage of Buddhahood.'
(Sayings and Doings of Pai-Chang, p 78)
And from Baizhang's Dharma-brother Dazhu Huihai:
'Sudden Enlightenment means liberation during this lifetime. Just as a lion-cub, from the moment it is born, is a real lion, likewise anyone who practices the Sudden-Enlightenment method has, from the moment he begins his practice, already entered the Buddha-Stage. Just as the bamboo-shoots growing in springtime are not different from the parent bamboo-shoots, because they are also empty inside, likewise anyone who practices the Sudden-Enlightenment method to rid himself suddenly of false thought abandons, like the Buddhas, the sense of an ego and a personality forever. Being absolutely deep, still and void, he is, then, without an iota of difference, equal to the Buddhas.'
(Treatise On Entering The Tao of Sudden Enlightenment)
See more from two modern Chan teachers:
Enlightenment and Buddhahood by Sheng-yen
Gradual Cultivation and Sudden Enlightenment by Wei Chueh
