One verse

Srimad Bhagavatam 4.8.72

4.8.72

त्रिरात्रान्ते त्रिरात्रान्ते कपित्थबदराशन: । आत्मवृत्त्यनुसारेण मासं निन्येऽर्चयन्हरिम् ॥ ७२ ॥

tri-ratrante tri-ratrante kapittha-badarasanah atma-vrtty-anusarena masam ninye ’rcayan harim

tri
three
ratra-ante
at the end of night
tri
three
ratra-ante
at the end of night
kapittha-badara
fruits and berries
asanah
eating
atma-vrtti
just to preserve the body
anusarena
as it was necessary, minimum
masam
one month
ninye
passed away
arcayan
worshiping
harim
the Supreme Personality of Godhead.

For the first month Dhruva Maharaja ate only fruits and berries on every third day, only to keep his body and soul together, and in this way he progressed in his worship of the Supreme Personality of Godhead.