One verse

Srimad Bhagavatam 2.9.8

2.9.8

दिव्यं सहस्राब्दममोघदर्शनो जितानिलात्मा विजितोभयेन्द्रिय: । अतप्यत स्माखिललोकतापनं तपस्तपीयांस्तपतां समाहित: ॥ ८ ॥

divyam sahasrabdam amogha-darsano jitanilatma vijitobhayendriyah atapyata smakhila-loka-tapanam tapas tapiyams tapatam samahitah

divyam
pertaining to the demigods in the higher planets
sahasra
one thousand
abdam
years
amogha
spotless, without a tinge of impurity
darsanah
one who has such a vision of life
jita
controlled
anila
life
atma
mind
vijita
controlled over
ubhaya
both
indriyah
one who has such senses
atapyata
executed penance
sma
in the past
akhila
all
loka
planet
tapanam
enlightening
tapah
penance
tapiyan
extremely hard penance
tapatam
of all the executors of penances
samahitah
thus situated

Lord Brahma underwent penances for one thousand years by the calculations of the demigods. He heard this transcendental vibration from the sky, and he accepted it as divine. Thus he controlled his mind and senses, and the penances he executed were a great lesson for the living entities. Thus he is known as the greatest of all ascetics.