SB 10.34.1
sri-suka uvaca
ekada deva-yatrayam
gopala jata-kautukah
anobhir anadud-yuktaih
prayayus te ’mbika-vanam
Translation:
Sukadeva Gosvami said: One day the cowherd men, eager to take a trip to worship Lord Siva, traveled by bullock carts to the Ambika forest.
Purport:
According to Srila Jiva Gosvami, the word ekada here indicates the occasion of Siva-ratri. He further mentions that Ambikavana is in Gujarat province, near the city of Siddhapura. Srila Visvanatha Cakravarti Thakura adds that the departure of the cowherd men specifically took place on the fourteenth lunar day of the dark fortnight of the month of Phalguna. Srila Visvanatha Cakravarti also quotes authorities who claim that Ambikavana lies on the bank of the Sarasvati River, northwest of Mathura. Ambikavana is notable because within it are deities of Sri Siva and his wife, goddess Uma.