The Shurangama Sutra, Volume 5: Upāli's Method of Perfect Penetration among the Twenty-Five Saints

Then Upāli rose from his seat, prostrated at the Buddha’s feet, and addressed the Buddha, saying: "I personally followed the Buddha when he left the palace by scaling the city walls at midnight to renounce household life. I witnessed with my own eyes the Tathāgata’s six years of arduous practice. I beheld firsthand how the Tathāgata subdued all demonic obstructions, vanquished all non-Buddhist paths, and liberated himself from worldly cravings and defilements. Having received the Buddha’s teachings and precepts, I strictly upheld them—even down to the three thousand dignified conducts, the eighty thousand subtle practices, and the purification of both inherent karmic obstacles and obstructive karmic hindrances—until my body and mind attained complete stillness and I became an Arhat. Within the Buddha’s assembly, I am recognized as the foremost in upholding the Vinaya, serving as its model and exemplar. The Buddha himself certified my purity of body and mind, and the community regards me as supreme in maintaining precepts and cultivating conduct. Now that the Buddha inquires about perfect penetration, I achieved it by first disciplining the body, whereby the physical form attained complete freedom—never violating any monastic precept. After restraining bodily actions, I progressively disciplined the mind, enabling it to penetrate the realm of the five aggregates. Ultimately, my body and mind became unimpeded in all phenomena. Thus, I consider the cultivation of precepts to discipline body and mind as the foremost means to perfect penetration."

Explanation: Upāli rose from his seat, prostrated at the Buddha’s feet, and replied: "I personally followed the Buddha when he scaled the city walls at midnight to renounce household life and cultivate the path in the snowy mountains. I witnessed with my own eyes the Tathāgata’s six years of diligent practice. I beheld firsthand how the Thus Come One subdued all demonic obstructions, vanquished all non-Buddhist paths, and liberated himself from the afflictions of worldly cravings and defilements. Having received the Buddha’s instructions on precepts, I rigorously upheld them—down to the three thousand subtle acts of purity, the eighty thousand minute defilements, the inherent karmic obstacles, and the obstructive hindrances from past karmic actions—all of which were eradicated. My mind became purified, my body and mind attained stillness, and I became an Arhat."

"Among the Buddha’s Bhikṣu assembly, I am foremost in upholding precepts, serving as the model and standard for monastic discipline. The Buddha personally certified the purity of my body and mind, and the community regards me as supreme in maintaining precepts and cultivating conduct. Now that the Buddha asks about the method of perfect penetration, I achieved it by first restraining the body, whereby the physical form attained complete freedom—never transgressing any monastic precept. After disciplining bodily conduct, I progressively restrained mental activities, enabling the mind to penetrate the realm of the five aggregates. Ultimately, my body and mind became unimpeded in all phenomena. I consider the cultivation of precepts to discipline body and mind as the foremost means to perfect penetration."

During the Buddha’s era of the True Dharma, perfect adherence to precepts alone could lead to the realization of fruition, even up to the fourth stage of Arhatship. However, in the Dharma-Ending Age, due to the inferior faculties of sentient beings and the contamination of the living environment, upholding precepts alone can no longer lead to fruition. One must cultivate precepts, meditative concentration, and wisdom simultaneously; only when all are perfected can fruition be attained. If one fails to observe the precepts, realization becomes even more unattainable, for a turbid and impure mind cannot give rise to meditative concentration or wisdom.