SB 4.8.73

dvitīyaṁ ca tathā māsaṁ
 ṣaṣṭhe ṣaṣṭhe ’rbhako dine
tṛṇa-parṇādibhiḥ śīrṇaiḥ
 kṛtānno ’bhyarcayan vibhum
dvitīyam — the next month; ca — also; tathā — as mentioned above; māsam — month; ṣaṣṭhe ṣaṣṭhe — every sixth day; arbhakaḥ — the innocent boy; dine — on days; tṛṇa-parṇa-ādibhiḥ — by grasses and leaves; śīrṇaiḥ — which were dry; kṛta-annaḥ — made for his food; abhyarcayan — and thus continued his method of worship; vibhum — for the Supreme Personality of Godhead.
In the second month Dhruva Mahārāja ate only every six days, and for his eatables he took dry grass and leaves. Thus he continued his worship.