Shiva Purana
कृष्णेन च कृतं नित्यं बदरीपर्वतोत्तमे ॥ पूजनं तु शिवस्यैव सप्तमासावधि स्वयम् ॥ ४८ ॥
Kṛṣṇa himself performed the worship of Śiva on the excellent mountain Badari for seven months.
english translation
kRSNena ca kRtaM nityaM badarIparvatottame ॥ pUjanaM tu zivasyaiva saptamAsAvadhi svayam ॥ 48 ॥
hk transliteration by Sanscript