Manusmriti
शुद्ध्येद् विप्रो दशाहेन द्वादशाहेन भूमिपः । वैश्यः पञ्चदशाहेन शूद्रो मासेन शुध्यति ॥ ८३ ॥
A Brahmana shall be pure after ten days, a Kshatriya after twelve, a Vaisya after fifteen, and a Sudra is purified after a month.
english translation
zuddhyed vipro dazAhena dvAdazAhena bhUmipaH । vaizyaH paJcadazAhena zUdro mAsena zudhyati ॥ 83 ॥
hk transliteration by Sanscript