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

Having last month considered the Buddha’s prediction for Pūrṇa, we repeat in gāthās the Buddha’s description of Pūrṇa’s ability to employ expedients.

Thereupon the Buddha, wishing to repeat what he had said, sang in gāthās:

Bhikṣus, 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 Śrāvakas or cause-knowers,
And teach the people with innumerable expedients.

Saying to the innumerable living beings, [for instance,]
“We are Śrāvakas.
We are far from the enlightenment of the Buddha,”
They save them, and cause them to attain [Śrāvakahood]
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 Śrāvakas.
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.

Under hundreds of thousands of millions of past Buddhas,
This Pūrṇa practiced strenuously what he should do.
He expounded and protected
The teachings of those Buddhas.

In order to obtain unsurpassed wisdom,
He became the most excellent disciple
Of those Buddhas.
He was learned and wise.
He expounded the Dharma without fear,
And made his listeners rejoice.
He was never tired
Of helping those Buddhas do their work.

He obtained great supernatural powers
And the four kinds of unhindered eloquence.
Seeing who was clever, and who was dull,
He always expounded the Pure Dharma.

He expounded the dharma of the Great Vehicle
To hundreds of thousands of millions of living beings,
And caused them to dwell in the Dharma
So that the worlds of those Buddhas might be purified.

The Daily Dharma from Oct. 6, 2022, offers this:

My disciples are performing
The Bodhisattva practices secretly
Though they show themselves in the form of Śrāvakas.
They are purifying my world.

The Buddha sings these verses in Chapter Eight of the Lotus Sūtra. The Śrāvakas are those who hear the teachings of the Buddha and put it into practice only for themselves. They are concerned with ending their own suffering and do not believe they have the capacity to reach the Buddha’s enlightenment. But because they can serve as an example to those who are also unsure about receiving this great wisdom, they can be an inspiration to make progress on the path. With the Lotus Sūtra, the Buddha declares that all beings have the capacity for enlightenment, and reveals that all of our pursuits are for the sake of benefiting others. It is when we realize this directly and openly that we perform the Bodhisattva practice, the selfless effort of awakening the world.