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

Having last month witnessed the Bodhisattva-mahāsattvas as many as the particles of dust of one thousand worlds vow to expound this sūtra, we see the World-Honored One display his great supernatural powers.

Thereupon the World-Honored One displayed his great supernatural powers in the presence of the multitude, which included not only the many hundreds of thousands of billions of Bodhisattva-mahāsattvas who had already lived in this Sahā-World [before the arrival of the Bodhisattvas from underground], headed by Mañjuśrī, but also bhikṣus, bhikṣunīs, upāsakās, upāsikās, gods, dragons, yakṣas, gandharvas, asuras, garuḍas, kiṃnaras, mahoragas, men and nonhuman beings. He stretched out his broad and long tongue upwards until the tip of it reached the World of Brahman. Then he emitted rays of light with an immeasurable variety of colors from his pores. The light illumined all the worlds of the ten quarters. The Buddhas who were sitting on the lion-like seats under the jeweled trees also stretched out their broad and long tongue and emitted innumerable rays of light. Śākyamuni Buddha and the Buddhas under the jeweled trees displayed these supernatural powers of theirs for one hundred thousand years. Then they pulled back their tongues, coughed at the same time, and snapped their fingers. 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. By the supernatural powers of the Buddhas, the living beings of those worlds, including gods, dragons, yakṣas, gandharvas, asuras, garuḍas, kiṃnaras, and mahoragas, men and nonhuman beings, saw the many hundreds of thousands of billions of Buddhas sitting on the lion-like seats under the jeweled trees in this Sahā-World. They also saw Śākyamuni Buddha sitting by the side of Many-Treasures Tathāgata on the lion-like seat in the stupa of treasures. They also saw that the many hundreds of thousands of billions of Bodhisattva-mahāsattvas and the four kind of devotees were surrounding Śākyamuni Buddha respectfully. Having seen all this, they had the greatest joy that they had ever had.

Ryusho Jeffus Shonin‘s Lecture on the Lotus Sutra offers this:

When the bodhisattvas who appeared from beneath the ground made their vow to carry out their practice of the Lotus Sutra in the Saha World after the death of the Buddha, immediately the Buddha gave his assent and praised their vow. There is no place in the sutra where the Buddha gives such a dramatic indicator of his pleasure. The Buddha immediately showed his supernatural powers to all present at the ceremony that is still continuing. His powers were displayed to the worlds of the universe in the ten quarters. He stretched out his long broad tongue, and he also emitted rays of light in various colors from the pores of his skin. All of this is not only seen in the other worlds but allows those in this world to see into those other worlds. All of this causes the other Buddhas, the replica Buddhas, to do the same, as well as coughing and snapping their fingers together. The snapping of fingers and coughing are devices employed by the Buddha to gain attention to an important teaching. And all of the various supernatural phenomena mentioned at this point in the Lotus Sutra serve to further demonstrate the importance of the Buddha accepting the vow made by the Bodhisattvas from Beneath the Ground.Lecture on the Lotus Sutra