Pakiṇṇaka 5

The Buddha was staying at Sāvatthī. … to bathe. (Thullanandā) came out first and put on a woman’s ornaments. The bhikkhunīs for this reason went and informed the World-honored One. … She answered: “I really did this.” The Buddha said: “From now on, it’s no longer allowed to wear women’s ornaments. ‘Women’s ornaments’ means diadems, earrings, bells, necklaces, fingerrings, bracelets for arms and legs, and similar items. All women’s ornaments may not be worn. If (a bhikkhunī) wears one, she breaks a minor vinaya rule. If she has an abscess on her body, and she applies medicine and bandages it, there’s no offense.” This is called the rule on women’s ornaments.