Shiva Purana
पौषे पुष्यनक्षत्रे कुर्यान्नीराजनं विभोः ॥ माघे मघाख्ये नक्षत्रे प्रदद्याद्घृतकंबलम् ॥ ६ ॥
In the month of Dec-Jan. when the moon is in the asterism Puṣya he shall perform the rite of Nīrājana to the lord. In the month of Jan-February in the Maghā star he shall make the charitable gifts of ghee and woollen blanket.
english translation
pauSe puSyanakSatre kuryAnnIrAjanaM vibhoH ॥ mAghe maghAkhye nakSatre pradadyAdghRtakaMbalam ॥ 6 ॥
hk transliteration by Sanscript