[1] At that time the Buddha, the Blessed One, was dwelling at Vesālī, at the Gotamaka shrine (Gotamake cetiye). Now at that time the triple robe (ticīvara) had been allowed by the Blessed One for the bhikkhus. The group-of-six bhikkhus, thinking, "The triple robe has been allowed by the Blessed One," entered the village with one triple robe, stayed in the monastery with another triple robe, and went down to bathe with yet another triple robe.
Those bhikkhus who were of few wishes, contented, conscientious, scrupulous, and desirous of the training criticized, complained, and spread it about, saying: "How can the group-of-six bhikkhus keep an extra robe (atirekacīvara)?"
Then those bhikkhus reported this matter to the Blessed One. Then the Blessed One, on that ground, in that connection, had the Saṅgha of bhikkhus convened and questioned the group-of-six bhikkhus: "Is it true, as is said, bhikkhus, that you keep an extra robe?"
"It is true, Blessed One."
The Buddha, the Blessed One, rebuked them: "It is unbecoming, foolish men, unsuitable, improper, unworthy of an ascetic, not allowable, not to be done. How can you, foolish men, keep an extra robe? This, foolish men, is neither for the confidence of those without confidence nor for the increase of those who have confidence …
"And thus, bhikkhus, you should recite this training rule (sikkhāpada): 'Whatever bhikkhu should keep an extra robe, there is an offense entailing relinquishment with confession (nissaggiyaṃ pācittiyaṃ).'"
And thus this training rule came to be laid down by the Blessed One for the bhikkhus.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.