Day 31 covers Chapter 27, King Wonderful-Adornment as the Previous Life of a Bodhisattva.

Having last month met Cloud-Thunderpeal-Star-King-Flower-Wisdom Buddha, King Wonderful-Adornment learns of his future Buddhahood.

“Thereupon Cloud-Thunderpeal-Star-King-Flower-Wisdom Buddha said to the four kinds of devotees, ‘Do you see this King Wonderful-Adornment standing before me with his hands joined together, or not? This king will become a bhiksu under me, strenuously study and practice the various ways to the enlightenment of the Buddha, and then become a Buddha called Sala-Tree-King in a world called Great-Light in a kalpa called Great-Height-King. Sala-Tree-King Buddha will be accompanied by innumerable Bodhisattvas and Sravakas. The ground of his world will be even. [King Wonderful-Adornment) will have these merits.’

“Thereupon the king abdicated from the throne in favor of his younger brother, renounced the world, and with his wife, two sons, and attendants, practiced the Way under that Buddha. After he renounced the world, the king acted according to the Sutra of the Lotus Flower of the Wonderful Dharma constantly and strenuously for eighty-four thousand years. Then he practiced the samadhi for the adornment of all pure merits. Then he went up to the sky seven times as high as the tala-tree, and said to that Buddha, ‘World-Honored One! These two sons of mine did the work of the Buddha. They converted me from wrong views by displaying wonders. They caused me to dwell peacefully in your teachings. They caused me to see you. These two sons of mine are my teachers. They appeared in my family in order to benefit me. They inspired the roots of good which I had planted in my previous existence.’

The Lecture on the Lotus Sutra offers this explanation of how we can do the work of the Buddha:

In the story of King Wonderful-Adornment in Chapter 27, the two sons who vow to practice Buddhism and then vow to convert their father do so because they are able to manifest the benefits of their Buddhist practice. The truth of the teaching enables them to change their lives, giving them the joy of life and the capacity to turn around and save their father. Their faith and seeking spirit led them to Buddhism and their benefit enables them to share it.
Lecture on the Lotus Sutra