The Śūraṅgama Sūtra, Volume V: The Dharma Gate of Perfect Penetration of the Twenty-Five Saints - Pūrṇa

Pūrṇa Maitrāyaṇīputra immediately rose from his seat. He prostrated at the Buddha's feet and addressed the Buddha, saying: "Since beginningless kalpas, I have possessed unhindered eloquence. I have expounded the truths of suffering and emptiness, profoundly penetrating the true nature of reality. Thus, even the secret Dharma gates of as many Tathāgatas as the sands of the Ganges, I have subtly expounded and revealed to the assembly without fear. The World-Honored One, knowing my great eloquence, taught me to develop it through the wheel of sound. Before the Buddha, I aided in turning the Dharma wheel. Through the lion's roar, I attained Arhatship. The World-Honored One confirmed me as unsurpassed in expounding the Dharma. The Buddha now inquires about perfect penetration. I used the sound of the Dharma to subdue the Māras and adversaries, extinguishing all outflows. This is foremost."

Explanation: Pūrṇa Maitrāyaṇīputra rose from his seat, prostrated at the Buddha's feet, and said to the Buddha: "Since beginningless kalpas, I have possessed superior wisdom and unhindered eloquence, expounding the Four Noble Truths of suffering and emptiness within the five aggregates to sentient beings, deeply understanding the true nature of all dharmas. Possessing such great eloquence, even the secret Dharma gates of Tathāgatas as numerous as the sands of the Ganges, I could exquisitely expound and reveal them to the assembly without fear regarding such profound Dharma. The World-Honored One, knowing my great eloquence, instructed me to fully develop my unhindered eloquence, using sound to teach and transform sentient beings. Thus, before the Buddha, I was able to aid in turning the Dharma wheel to liberate beings. Because I excelled at the lion's roar, I attained the fourth fruition of great Arhatship. The World-Honored One confirmed me as foremost among the Buddha's disciples in expounding the Dharma, with none surpassing me. Now the Buddha asks about the method of perfect penetration I cultivated and realized. I used the sound of my Dharma exposition to subdue the Māras and adversaries, extinguishing all afflictions. This is the foremost method of perfect penetration I cultivated and realized."

Pūrṇa not only possessed profound wisdom but also exceptional verbal expressiveness. Therefore, since beginningless kalpas, he had continuously aided the Buddha in turning the Dharma wheel. Having eradicated afflictions and attained the fourth fruition of Arhatship, he could also expound the secret Dharma gates of the Tathāgatas. Thus, the level of his realization was equivalent to that of a Bodhisattva of the eighth ground or above. These great disciples of the Buddha all had significant origins; they were all Buddhas and Bodhisattvas who compassionately returned, manifesting as Śrāvakas to assist the Buddha in propagating the Dharma. These great disciples possessed great spiritual powers but did not display them lightly, appearing similar to ordinary people. Even during famines when they could not obtain almsfood, Pūrṇa would rather eat cow dung than use spiritual powers to manifest food. The Buddha also did not allow Maudgalyāyana and others to use their supernormal foot power to fly to Uttarakuru to seek alms. In truth, these great Arhats could completely do without food, but to demonstrate the Dharma and appear identical to ordinary monastics, thereby guiding the bhikṣus, they refrained from using spiritual powers. This was also done for the sake of monastics in future generations, lest those without spiritual powers be ridiculed by sentient beings, causing them to create negative karma.