[146] Now at that time a certain bhikkhu went about for alms with long nails. A certain woman, seeing him, said to that bhikkhu: "Come, venerable sir, engage in sexual intercourse." "Enough, sister; that is not allowable." "If, venerable sir, you will not engage in it, then right now I will scratch my own limbs with my nails and raise an outcry: 'This bhikkhu is molesting me!'" "Know that for yourself, sister." Then that woman, having scratched her own limbs with her nails, raised an outcry: "This bhikkhu is molesting me!" People ran up and seized that bhikkhu. But those people saw the skin and blood on that woman's nails, and having seen it, [they concluded:] "This is the doing of this very woman; the bhikkhu is not the doer," and they released that bhikkhu.
Then that bhikkhu, having gone to the monastery, told this matter to the bhikkhus. "But do you, friend, wear long nails?" "It is so, friends." Those bhikkhus who were of few wishes … were annoyed, complained, and spread it about: "How indeed can a bhikkhu wear long nails?" Then those bhikkhus reported this matter to the Blessed One. … "Bhikkhus, long nails are not to be worn; whoever should wear them commits an offense of wrongdoing (dukkaṭa)."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.