THUS I HEARD:
At one time the Gracious One was dwelling near Rājagaha, in Bamboo Wood, at the Squirrels’ Feeding Place. Then at that time the leper known as Suppabuddha Wide Awake was in Rājagaha, a poor man, a wretched man, a miserable man.
Then at that time the Gracious One was sitting teaching Dhamma surrounded by a great assembly. The leper Suppabuddha saw while still far away that great crowd of people assembled together. Having seen that, this occurred to him:
“Undoubtedly in this place some comestibles and edibles will be distributed. Well now, I could go to that great crowd of people, perhaps I will get some comestibles or edibles in this place.”
Then the leper Suppabuddha went to that great crowd of people. The leper Suppabuddha saw the Gracious One sat teaching Dhamma surrounded by a great assembly. Having seen that, this occurred to him:
“Here there are no comestibles or edibles being distributed, this ascetic Gotama is teaching Dhamma to the assembly. Perhaps I also could hear the Dhamma”, and he sat down right there and then, thinking: “I will also listen to the Dhamma.”
Then the Gracious One, applied his mind and encompassed fully the whole of that assembly with his mind, thinking: “Who here is able to understand the Dhamma?”
The Gracious One saw the leper Suppabuddha sat in that assembly, and having seen him, this occurred to him: “This one here is able to understand the Dhamma”, and having regard to the leper Suppabuddha he related a gradual talk, that is to say: talk on giving, talk on virtue, talk on heaven, the danger, degradation, and defilement of sensual desires, and the advantages in renunciation—these he explained. When the Gracious One knew that the leper Suppabuddha was of ready mind, malleable mind, unhindered mind, uplifted mind, trusting mind, then he explained the Dhamma teaching the Awakened Ones have discovered themselves: suffering, origination, cessation, path.
Just as it is known that a clean cloth without a stain would take the dye well, so to the leper Suppabuddha on that very seat, the dust-free, stainless Vision-of-the-Dhamma arose: “Whatever has the nature of arising, all that has the nature of ceasing.”
Then the leper Suppabuddha having seen the Dhamma, attained the Dhamma, understood the Dhamma, penetrated the Dhamma, crossed over uncertainty, being without doubts, attained full confidence, having become independent of others in the Teacher’s teaching, after rising from his seat went to the Gracious One, and after going and worshipping the Gracious One, he sat down at one side. While he was sitting on one side the leper Suppabuddha said this to the Gracious One:
“Excellent, reverend Sir! Excellent reverend Sir! Just as, reverend Sir, one might set upright what has been overturned, or open up what has been closed, or show a path to one who is lost, or bear an oil lamp in the darkness so that those with vision can see forms, just so has the Dhamma been explained by the Gracious One in countless ways. I go, reverend Sir, to the Gracious One for refuge, and to the Dhamma, and to the Community of monks. Please bear it in mind, reverend Gotama, that I am a lay follower who has gone for refuge from today forward for as long as I have the breath of life.”
Then the Gracious One instructed, roused, enthused, and cheered the leper Suppabuddha with a Dhamma talk, and after greatly rejoicing and gladly receiving this word of the Gracious One, after rising from his seat, worshipping and circumambulating the Gracious One, he went away.
Then not long after the leper Suppabuddha had gone a cow with a young calf having attacked him, deprived him of life. Then many monks went to the Gracious One, and after going and worshipping the Gracious One, they sat down on one side. While sat on one side those monks said this to the Gracious One:
“That leper called Suppabuddha, reverend Sir, who was instructed, roused, enthused, and cheered by the Gracious One with a Dhamma talk—he has died. What is his destination? What is his future state?”
“A wise man, monks, was Suppabuddha, who practiced Dhamma in accordance with the Dhamma, and did not trouble me on account of the Dhamma. The leper Suppabuddha, monks, through the destruction of three fetters, is a stream-enterer, not subject to the fall, and is assured of arriving at Full Awakening.”
When that was said, a certain monk said this to the Gracious One: “What was the reason, reverend Sir, what was the cause, through which the leper Suppabuddha became a poor man, a wretched man, a miserable man?”
“Formerly, monks, the leper Suppabuddha was a son of a wealthy merchant in this very Rājagaha. While going to his pleasure park he saw the Pacceka Buddha Tagarasikkhī entering the city for alms, and having seen him, this occurred to him: “Who is this leper roaming around with his leper’s robe?” And having spat, and circumambulated him disrespectfully on the left side, he went away.
As a result of that deed of his for many years, for many hundreds of years, for many thousands of years, for many hundreds of thousands of years, he boiled in the nether regions. And as a result of the remaining part of that deed of his he became a leper in this very Rājagaha, a poor man, a wretched man, a miserable man.
But he came to the Dhamma and Discipline taught by the Realised One, and obtained faith, obtained virtue, obtained learning, obtained liberality, obtained wisdom. After coming to the Dhamma and Discipline taught by the Realised One, and obtaining faith, obtaining virtue, obtaining learning, obtaining liberality, obtaining wisdom, at the break up of the body, after death, he arose in a fortunate destiny, in the world of Heaven, in the companionship of the Tāvatiṃsa devas. And there he surely outshines the other devas with his beauty and repute.”
Then the Gracious One, having understood the significance of it, on that occasion uttered this exalted utterance:
“As a man with vision, while he is endeavouring, would avoid dangerous paths,
So a wise man in the world of the living, should avoid bad deeds.”
Source: https://suttacentral.net/ud5.3 Suppabuddhakuṭṭhi Sutta Ud 5.3 Ud 48