SB 4.8.73
dvitiyam ca tatha masam
sasthe sasthe ’rbhako dine
trna-parnadibhih sirnaih
krtanno ’bhyarcayan vibhum
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In the second month Dhruva Maharaja ate only every six days, and for his eatables he took dry grass and leaves. Thus he continued his worship.