Khuddakavatthukkhandhaka

Vinayapiṭaka · Cūḷavagga (2) · Vol. 7 · Section 22

[22] Now at that time the group-of-six bhikkhus (chabbaggiyā bhikkhū) wore woolen cloaks with the fleece on the outside. People complained, criticized, and spread it about: "… just like householders who enjoy sensual pleasures." They reported this matter to the Blessed One. … "Bhikkhus, a woolen cloak with the fleece on the outside should not be worn. Whoever should wear one commits an offense of wrong-doing (dukkaṭa)."

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 3 other places