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.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
द्वितीयं च तथा मासं षष्ठे षष्ठेऽर्भको दिने । तृणपर्णादिभिः शीर्णैः कृतान्नोऽभ्यर्चयद्विभुम्
dvitīyaṃ ca tathā māsaṃ ṣaṣṭhe ṣaṣṭhe'rbhako dine | tṛṇaparṇādibhiḥ śīrṇaiḥ kṛtānno'bhyarcayadvibhum
SB 4.8.73