He was the son of a very wealthy treasurer of Bārāṇasī, and was brought up in great luxury, living in three mansions, according to the seasons and surrounded with all kinds of pleasures. Impelled by antecedent conditions, he saw one night the indecorum of his sleeping attendants, and, greatly distressed, put on his gold slippers and left the house and the town, non-humans opening the gates for him. He took the direction of Isipatana, exclaiming: “Alas! What distress! Alas! What danger!” The Buddha saw him in the distance and called to him, “Come Yasa, here is neither distress nor danger.” Filled with joy, Yasa took off his slippers and sat beside the Buddha. The Buddha taught him a graduated discourse, and when he had finished teaching the Four Noble Truths, Yasa attained realisation of the Dhamma.

To Yasa’s father, too, who had come in search of his son, the Buddha taught the Doctrine, having first made Yasa invisible to him. (This is given as an example of the Buddha’s psychic power, Vism.393). At the end of the discourse he acknowledged himself as the Buddha’s follower, thus becoming the first disciple to take threefold refuge (tevācika upāsaka), and Yasa, who had been listening, became an Arahant. When, therefore, Yasa’s presence became known to his father, who asked him to return to his grieving mother, the Buddha declared that household life had no attractions for Yasa and granted his request to be admitted to the Order. The next day, at the invitation of Yasa’s father, he went, accompanied by Yasa, to his house, and there, at the conclusion of the meal, he taught Yasa’s mother and other members of the household, who all became his followers, thus becoming the first female disciples to take the threefold refuge (tevācikā upāsikā). When Yasa’s intimate friends, Vimala, Subāhu, Puṇṇaji, and Gavampati, heard of Yasa’s ordination they followed his example and joined the Order, attaining Arahantship in due course, as did fifty others of Yasa’s former friends and acquaintances (Vin.i.15-20; DhA.i.72).

In the time of Sumedha Buddha, Yasa was a king of the Nāgā and invited the Buddha and his monks to his abode, where he showed them great honour and hospitality. He then gave costly robes to the Buddha and to each monk a pair of valuable robes. In the time of Siddhattha Buddha he was a Treasurer, and offered the seven kinds of jewels at the Bodhi tree. In the time of Kassapa Buddha he was a monk. For eighteen thousand world-cycles he was a deva king and one thousand times he was king of men. Wherever he went he had a gold canopy, and in his last life over his funeral pyre was a gold canopy (ThagA.i.232 f). He is evidently identical with Sabbadāyaka of the Apadāna (Ap.i.333 f). A verse attributed to him is found in the Theragāthā (vs.117).

Yasa is often quoted as one who enjoyed great luxury in his lay life (AA.ii.596).

The Dhammapada Commentary (DhA.i.82 f ) states that, in a past life, Yasa and his four companions wandered about engaged in various acts of social service. One day they came across the dead body of a pregnant woman, which they took to the cemetery to be cremated. There the others went away, leaving Yasa to finish the work. While burning the corpse his mind was filled with thoughts of the foulness of the human body; he drew the attention of his friends to this idea, and, later, of his parents and wives, all of whom approved of what he said. For this reason Yasa felt revulsion against the household life, and his friends and members of his family were able to realise the Dhamma early in the Buddha’s career.

The ordination of Yasa was one of the scenes of the Buddha’s life to be sculptured in the Relic Chamber of the Mahā Thūpa (Mhv.xxx.79).

According to the Aṅguttaranikāya Commentary (AA.i.218 f), Sujātā Senānīdhītā (who gave the Buddha a meal of milk-rice just before his Enlightenment) was Yasa’s mother. She became a Stream-winner after listening to the Buddha’s discourse.