viriñco ’pi tathā cakre
divyaṁ varṣa-śataṁ tapaḥ
ātmany ātmānam āveśya
yathāha bhagavān ajaḥ
maitreyaḥ uvāca—the great sage Maitreya said; viriñcaḥ—Brahmā; api—also; tathā—in that manner; cakre—performed; divyam—celestial; varṣa-śatam—one hundred years; tapaḥ—penances; ātmani—unto the Lord; ātmānam—his own self; āveśya—engaging; yathā āha—as it was spoken; bhagavān—the Personality of Godhead; ajaḥ—the unborn.
The greatly learned sage Maitreya said: O Vidura, Brahmā 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.
Link to this page: https://prabhupadabooks.com/sb/3/10/4