Revākhaṇḍa ascribed to the Vāyupurāṇa (RKV) 63.5

63.5

kārttikasya caturdaśyāmaṣṭamyāṃ ca viśeṣataḥ /
snāpayed girijānāthaṃ dadhidugdhena sarpiṣā //

especially on the fourteenth and on the eighth day of the month of Kārttika,
should bathe the lord of the Mountain's Daughter with yogurt, milk, and clarified butter;