[13] Now at that time the bhikkhus of the group of six (chabbaggiyā) wore their hair long. People criticized, complained, and spread it about: "… just like householders who enjoy sensual pleasures" … They reported this matter to the Blessed One … "Bhikkhus, long hair is not to be worn; whoever should wear it commits an offense of wrong-doing (dukkaṭa). Bhikkhus, I allow it for two months, or two finger-breadths (duvaṅgula) in length."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.