Day 17 covers all of Chapter 12, Devadatta, and opens Chapter 13, Encouragement for Keeping This Sutra.

Because of Devadatta:

Devadatta was my teacher. He caused me to complete the six pāramitās. He caused me to have loving-kindness, compassion, joy and impartiality. He caused me to have the thirty-two major marks and the eighty minor marks [of the Buddha]. He caused me to have my body purely gilt. He caused me to have the ten powers and the four kinds of fearlessness. He caused me to know the four ways to attract others. He caused me to have the eighteen properties and supernatural powers [of the Buddha]. He caused me to have the power of giving discourses. I attained perfect enlightenment and now save all living beings because Devadatta was my teacher.

Good to hear:

Good men or women in the future who hear this chapter of Devadatta of the Sūtra of the Lotus Flower of the Wonderful Dharma with faithful respect caused by their pure minds, and have no doubts [about this chapter], will not fall into hell or the region of hungry spirits or the region of animals. They will be reborn before the Buddhas of the worlds of the ten quarters. They will always hear this sūtra at the places of their rebirth. Even when they are reborn among men or gods, they will be given wonderful pleasures. When they are reborn before the Buddhas, they will appear in lotus-flowers.

The dragon-king daughter praised the Buddha:

You know the sins and merits
Of all living beings.
You illumine the worlds of the ten quarters.
Your wonderful, pure and sacred body
Is adorned with the thirty-two major marks
And with the eighty minor marks.

Gods and men are looking up at you.
Dragons also respect you.
None of the living beings
Sees you without adoration.

Only you know that I [am qualified to] attain Bodhi
Because I heard [the Dharma].
I will expound the teachings of the Great Vehicle
And save all living beings from suffering.

Despite the five impossibilities – a woman cannot become 1. the Brahman-Heavenly-King, 2. King Śakra, 3. King Māra, 4. a wheel-turning-holy-king, and 5. a Buddha – the 8-year-old daughter of Dragon-King Sāgara proved the skeptics wrong.

Having seen from afar that [the man who had been] the daughter of the dragon-king had become a Buddha and [begun to] expound the Dharma to the men and gods in his congregation, all the living beings of the Sahā-World, including Bodhisattvas, Śrāvakas, gods, dragons, the [six other kinds, that is, in total] eight kinds of supernatural beings, men, and nonhuman beings, bowed [to that Buddha] with great joy.

That is all but Accumulated-Wisdom Bodhisattva and Śāriputra, who “received the Dharma faithfully and in silence.”

In Chapter 13, Encouragement for Keeping This Sutra, Medicine-King Bodhisattva-mahāsattva and Great-Eloquence Bodhisattva-mahāsattva, together with their twenty thousand attendants who were also Bodhisattvas, vowed to the Buddha:

“World-Honored One, do not worry! We will keep, read, recite and expound this sūtra after your extinction. The living beings in the evil world after [your extinction] will have less roots of good, more arrogance, more greed for offerings of worldly things, and more roots of evil. It will be difficult to teach them because they will go away from emancipation. But we will patiently read, recite, keep, expound and copy this sūtra, and make various offerings to it. We will not spare even our lives [in doing all this].”

But the 500 Arhats and the eight thousand Śrāvakas vowed to expound the sūtra but not in the Sahā-World:

[T]he people of this Sahā-World have many evils. They are arrogant. They have few merits. They are angry, defiled, ready to flatter others, and insincere.

Even Maha-Prajāpatī Bhikṣuṇī, Yaśodharā Bhikṣuṇī, and their attendants couldn’t bring themselves to expound the sūtra in the Sahā-World.

Day 16 concludes Chapter 11, Beholding the Stupa of Treasures, and completes the Fourth Volume of the Sutra of the Lotus Flower of the Wonderful Dharma.

Beholding the stūpa of Treasures:

The Saintly Master, the World-Honored One,
Who had passed away a long time ago,
Came riding in the stūpa of treasures
To hear the Dharma [directly from me].
Could anyone who sees him
Not make efforts to hear the Dharma?

The Buddha’s replicas take their seats:

Those Buddhas came under the jeweled trees.
The trees are adorned with those Buddhas
Just as a pond of pure water is adorned
With lotus flowers.

The question:

(The Buddha said to the great multitude.)
Who will protect
And keep this sūtra,
And read and recite it
After my extinction?
Make a vow before me to do this!

Some easy task and some not so easy:

Good men! Think this over clearly!
It is difficult [To expound this sūtra].
Make a great vow to do this!

It is not difficult
To expound all the other sūtras
As many as there are sands
In the River Ganges.

It is not difficult
To grasp Mt. Sumeru
And hurl it to a distance
Of countless Buddha-worlds.

It is not difficult to move [a world]
[Composed of] one thousand million Sumeru-worlds
With the tip of a toe
And hurl it to another world.

It is not difficult
To stand in the Highest Heaven
And expound innumerable other sūtras
To all living beings.

It is difficult
To expound this sūtra
In the evil world
After my extinction.

It is not difficult
To grasp the sky,
And wander about with it
From place to place.

It is difficult
To copy and keep this sūtra
Or cause others to copy it
After my extinction.

It is not difficult
To put the great earth
On the nail of a toe
And go up to the Heaven of Brahman.

It is difficult
To read this sūtra
Even for a while in the evil world
After my extinction.

It is not difficult
To shoulder a load of hay
And stay unburned in the fire
At the end of the kalpa [of destruction].

It is difficult
To keep this sūtra
And expound it to even one person
After my extinction.

It is not difficult
To keep the store
Of eighty-four thousand teachings
Expounded in the sūtras
Composed of the twelve elements,
And expound it to people,
And cause the hearers to obtain
The six supernatural powers.

It is difficult
To hear and receive this sūtra,
And ask the meanings of it
After my extinction.

It is not difficult
To expound the Dharma
To many thousands of billions of living beings
As many as there are sands
In the River Ganges
So that they may be able
To obtain the benefits:
Arhatship and the six supernatural powers.

It is difficult
To keep This sūtra
After my extinction.

Since I attained
The enlightenment of the Buddha,
I have expounded many sūtras
In innumerable worlds.
This sūtra is
The most excellent.
To keep this sūtra
Is to keep me.

Day 15 completes Chapter 10, The Teacher and the Dharma, and introduces Chapter 11, Beholding the Stupa of Treasures.

The Buddha explains that the Lotus Sutra “is the most difficult to believe and the most difficult to understand” because it is “the store of the hidden core of all the Buddhas.”

Medicine-King, know this! Anyone who copies, keeps, reads and recites this sūtra, makes offerings to it, and expounds it to others after my extinction, will be covered by my robe. He also will be protected by the present Buddhas of the other worlds. He will have the great power of faith, the power of vows, and the power of roots of good. Know this! He will live with me. I will pat him on the head.

Living with the Buddha, covered in his robe.

Without the Lotus Sutra?

Medicine-King! Although many laymen or monks will practice the Way of Bodhisattvas, they will not be able to practice it satisfactorily, know this, unless they see, hear, read, recite, copy or keep this Sūtra of the Lotus Flower of the Wonderful Dharma or make offerings to it. If they hear this sūtra, they will. Anyone who, while seeking the enlightenment of the Buddha, sees or hears this Sūtra of the Lotus Flower of the Wonderful Dharma, and after hearing it, understands it by faith and keeps it, know this, will approach Anuttara-samyak-saṃbodhi.

And…

A man on a plateau, feeling thirsty,
Dug a hole in order to get water.
As long as he saw the dug-out lumps of earth were dry,
He knew that water was still far off.
When he found the earth wet and muddy,
He was convinced that water was near.

In the same manner, Medicine-King, know this!
Those who do not hear
The Sūtra of the Lotus Flower of the Wonderful Dharma
Are far from the wisdom of the Buddha.

What is required to expound the Lotus Sutra?

Medicine-King! How should the good men or women who live after my extinction expound this Sūtra of the Lotus Flower of the Wonderful Dharma to the four kinds of devotees when they wish to? They should enter the room of the Tathāgata, wear the robe of the Tathāgata, sit on the seat of the Tathāgata, and then expound this sūtra to the four kinds of devotees. To enter the room of the Tathāgata means to have great compassion towards all living beings. To wear the robe of the Tathāgata means to be gentle and patient. To sit on the seat of the Tathāgata means to see the voidness of all things.

And then suddenly, without warning, a giant stupa of treasures rises from the earth and hangs in the air and from inside a loud voice is heard to say:

“Excellent, excellent! You, Śākyamuni, the World-Honored One, have expounded to this great multitude the Sūtra of the Lotus Flower of the Wonderful Dharma, the Teaching of Equality, the Great Wisdom, the Dharma for Bodhisattvas, the Dharma Upheld by the Buddhas. So it is, so it is. What you, Śākyamuni, the World-Honored One, have expounded is all true.”