Day 13 covers all of Chapter 8, The Assurance of Future Buddhahood of the Five Hundred Disciples.
Having last month considered the prediction for Pūrṇa Bhikṣu, we hear from twelve hundred Arhats.
Thereupon the twelve hundred Arhats, who had already obtained freedom of mind, thought:
“We have never been so joyful before. How glad we shall be if we are assured of our future Buddhahood by the World-Honored One just as the other great disciples were!”
Seeing what they had in their minds, the Buddha said to Maha-Kāśyapa:
“Now I will assure these twelve hundred Arhats, who are present before me, of their future attainment of Anuttara-samyak-saṃbodhi one after another. My great disciple Kauṇḍinya Bhikṣu, who is among them, will make offerings to six billion and two hundred thousand million Buddhas, and then become a Buddha called Universal-Brightness, the Tathāgata, the Deserver of Offerings, the Perfectly Enlightened One, the Man of Wisdom and Practice, the Well-Gone, the Knower of the World, the Unsurpassed Man, the Controller of Men, the Teacher of Gods and Men, the Buddha, the World-Honored One. The others of the five hundred Arhats, including Uruvilvā-Kāśyapa, GayaKāśyapa, Nadī-Kāśyapa, Kālodāyin, Udāyin, Aniruddha, Revata, Kapphina, Bakkula, Cunda, and Svāgata, also will attain Anuttara-samyak-saṃbodhi, and become Buddhas also called Universal-Brightness.”
Nichiren writes of Aniruddha in his Letter to Hōren:
A Hinayāna sage known as Pratyekabuddha is incomparably superior to a śrāvaka. He is so great that he can stand in for the Buddha to appear in the world to save its people. It is said that there was once a hunter who in a time of famine gave a bowl of rice mixed with barnyard millet to a pratyekabuddha called Rita, and as a result he was rewarded with rebirth as a man of wealth in the human or heavenly world for as long as 91 kalpa (aeons). Aniruddha, one of the ten great disciples of the Buddha who is reputed to have mastered the divine-eye of heavenly beings to see through everything, is said to have been [the incarnation of) the hunter. Grand Master Miao-lê interprets this, “Although the bowl of barnyard millet rice has little value, the hunter donated all that he owned to a person of great merit. Therefore, the hunter was rewarded with such good fortune.” It means that although a bowl of millet rice was not much in value, it was presented to a noble person of Pratyekabuddha status, and this is the reason why he was able to be reborn with such good luck.
Hōren-shō, Letter to Hōren, Writings of Nichiren Shōnin, Volume 6, Followers I, Page 46