Day 25 covers all of Chapter 20, Never-despising Bodhisattva and introduces Chapter 21,  The Supernatural Powers of the Tathāgatas.

Chapter 20’s concluding gāthās say it all for me:

Never-Despising [Bodhisattva] met
Innumerable Buddhas after the end of his life.
He expounded this sūtra,
And obtained innumerable merits,
He quickly attained the enlightenment of the Buddha
By these accumulated merits.

Never-Despising [Bodhisattva] at that time
Was myself. The four kinds of devotees,
Who were attached to views at that time,
Were able to meet innumerable Buddhas
After they heard
The words of Never-Despising [Bodhisattva]:
“You will become Buddhas.”
They are now present here
In this congregation.

They are the five hundred Bodhisattvas
And the four kinds of devotees
Including men and women of pure faith,
Who are now hearing the Dharma from me.
In my previous existence I encouraged them
To hear this sūtra,
That is, the most excellent Dharma.
In all my previous existences
I taught them the Way to Nirvāṇa.
But really this is the sūtra
I taught them to keep.

This Sūtra of the Lotus Flower of the Wonderful Dharma
Can be heard only once
In hundreds of millions of billions of kalpas,
That is, in an inconceivable number of kalpas.

The Buddhas, the World-Honored Ones,
Expound this sūtra only once
In hundreds of millions of billions of kalpas,
That is, in an inconceivable number of kalpas.

Therefore, anyone who hears this sūtra
And practices the Way
After my extinction,
Should have no doubts about [this sūtra].

He should expound this sūtra with all his heart;
Then he will be able to meet Buddhas
Throughout all his existences,
And quickly attain the enlightenment of the Buddha.

Chapter 21 opens with a demonstration of the supernatural powers of the Tathāgatas’ tongue.

Now I understand that the long, broad tongues raised to the World of Brahman by the Buddhas signify their testament to the truth of the sutra. But what is the significance of:

Then they pulled back their tongues, coughed at the same time, and snapped their fingers.

Sure. Everyone, even a Buddha and his countless emanations, can be expected to cough after sticking out their tongue for 100,000 years. But the finger snap?

These two sounds [of coughing and snapping] reverberated over the Buddha-worlds of the ten quarters, and the ground of those worlds quaked in the six ways.