Shiva Purana
निषिद्धासेवनं चैव भस्मरुद्राक्षधारणम् ॥ पर्वण्यभ्यर्चनं देवि चतुर्दश्यां विशेषतः ॥ ५ ॥
It is forbidden to eat food and to wear ashes and rudraksha O Devi worship on the festivals especially on the fourteenth day.
english translation
niSiddhAsevanaM caiva bhasmarudrAkSadhAraNam ॥ parvaNyabhyarcanaM devi caturdazyAM vizeSataH ॥ 5 ॥
hk transliteration by Sanscript