Vaishnava Samhita. Narasimha Mehta Charitam I. Vol III Book VI Chp 15 Shloka 28

तथा मां पूजयन् पूर्वमुपमन्युश्च बालकः  |
क्षीरमेवार्थयन् किञ्चित् प्रपेदे क्षीरसागरम् ||

Long back, a young boy named Upamanyu worshipped Me and prayed for milk. He was rewarded with the pleasure of enjoying the ocean of milk itself.