Day 13 covers all of Chapter 8, The Assurance of Future Buddhahood of the Five Hundred Disciples.

Today we underline the emerging idea that there is only the Bodhisattva teaching and everyone will in time become a Buddha.

The chapter begins with Purna, who is considered to be foremost in expounding the Dharma among Sakyamuni’s top disciples. He will be foremost in expounding the Dharma many times again in the future. More to today’s point, he is not your ordinary sravaka:

Although he had the supernatural powers of Bodhisattvas, he performed brahma practices throughout his previous existence. Therefore, the people of the world of the Buddha under whom he performed brahma practices] thought that he was a Sravaka. He benefited many hundreds of thousands of living beings with this expedient, and also caused innumerable, asamkhya people to aspire for Anuttara-samyak-sambodhi. He did the work of the Buddha, that is, taught all living beings so that the world of the Buddha might be purified.

To make the point clearer:

He will always make efforts to teach all living beings strenuously so that the worlds of those Buddhas may be purified. He will perform the Way of Bodhisattvas step by step for innumerable, asamkhya kalpas, and then attain Anuttara-samyak-sambodhi in this world.

And in gathas:

Bhiksus, listen to me attentively!
The Way practiced by my sons
Is beyond your comprehension
Because they learned how to employ expedients.

Knowing that people wish to hear
The teachings of the Lesser Vehicle,
And that they are afraid of having the great wisdom,
[My sons, that is,] the Bodhisattvas transform themselves
Into Sravakas or cause-knowers,
And teach the people with innumerable expedients.

Saying to the innumerable living beings, [for instance,]
“We are Sravakas.
We are far from the enlightenment of the Buddha,”
They save them, and cause them to attain [Sravakahood]
Even the lazy people who wish to hear the Lesser Vehicle
Will become Buddhas with this expedient in the course of time.

My disciples are performing
The Bodhisattva practices secretly
Though they show themselves in the form of Sravakas.
They are purifying my world
Though they pretend to want little
And to shun birth-and-death.
In the presence of the people,
They pretend to have the three poisons and wrong views.
They save them with these expedients.
They change themselves into various forms.
If I speak of all their transformations,
The listeners will doubt me.

Underline My sons, that is, the Bodhisattvas transform themselves into Sravakas or cause-knowers, and teach the people with innumerable expedients. We’ll come back to this in later chapters.

But back in this chapter, we have assurances of future Buddhahood for “these 1,200 Arhats” and in particular Kaundinya Bhiksu.

The others of the five hundred Arhats, including Uruvilva-Kasyapa, Gaya-Kasyapa, Nadi-Kasyapa, Kalodayin, Udayin, Aniruddha, Revata, Kapphina, Bakkula, Cunda, and Svagata, also will attain Anuttara-samyak-samodhi, and become Buddhas also called Universal-Brightness.

With everyone dancing for joy with the news, we come to the Parable of the Priceless, in which a rich man sews a priceless gem into a friend’s garment while he sleeps. When he awakens he moves on, struggling to find food and shelter, satisfying himself with what work he can find, because he does not know he has this gem.

The point: These Arhats realize they forgot that in past lives the Buddha had instructed them on attaining Anuttara-samyak-samodhi.

World-Honored One! Now we see that we are Bodhisattvas in reality, and that we are assured of our future attainment of Anuttara-samyak-sambodhi. Therefore, we have the greatest joy that we have ever had.

And in gathas:

We are like the poor man.
In the long night you taught us
Out of your compassion towards us,
And caused us to aspire for unsurpassed [enlightenment].

Because we had no wisdom, we did not notice that.
The Nirvana we attained was only part [of your wisdom].
Satisfying ourselves with it,
We did not wish to attain anything more.

Now you have awakened us, saying:
“What you attained was not true extinction.
When you have the unsurpassed wisdom of the Buddha,
You will attain true extinction.”

Hearing from you that we are assured
Of becoming Buddhas one after another,
And that our worlds will be adorned,
We are joyful in body and mind.