Shiva Purana
पंचम्यां पौर्णमास्यां वा कृतप्राभातिकक्रियः ॥ लब्धानुज्ञस्तु गुरुणा स्नात्वा नियतमानसः ॥ १३ ॥
On the fifth or full moon day the morning rituals are performed Having obtained the permission of his spiritual master he took his bath and with a steady mind.
english translation
paMcamyAM paurNamAsyAM vA kRtaprAbhAtikakriyaH ॥ labdhAnujJastu guruNA snAtvA niyatamAnasaH ॥ 13 ॥
hk transliteration by Sanscript