The greatly learned sage Maitreya said: O Vidura, Brahma thus engaged himself in penances for one hundred celestial years, as advised by the Personality of Godhead, and applied himself in devotional service to the Lord

Expressions researched:
"The greatly learned sage Maitreya said: O Vidura, Brahma thus engaged himself in penances for one hundred celestial years, as advised by the Personality of Godhead, and applied himself in devotional service to the Lord"

Srimad-Bhagavatam

SB Canto 3

The greatly learned sage Maitreya said: O Vidura, Brahma thus engaged himself in penances for one hundred celestial years, as advised by the Personality of Godhead, and applied himself in devotional service to the Lord.

SB 3.10.4, Translation and Purport

The greatly learned sage Maitreya said: O Vidura, Brahma thus engaged himself in penances for one hundred celestial years, as advised by the Personality of Godhead, and applied himself in devotional service to the Lord.

That Brahmā engaged himself for the Personality of Godhead, Nārāyaṇa, means that he engaged himself in the service of the Lord; that is the highest penance one can perform for any number of years. There is no retirement from such service, which is eternal and ever encouraging.