Srimad Bhagavatam Canto 02, Chapter 09, Text 23

SB 2.9.23

pratyadistam maya tatra
tvayi karma-vimohite
tapo me hrdayam saksad
atmaham tapaso ’nagha
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
O sinless Brahma, you may know from Me that it was I who first ordered you to undergo penance when you were perplexed in your duty. Such penance is My heart and soul, and therefore penance and I are nondifferent.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
The penance by which one can see the Personality of Godhead face to face is to be understood as devotional service to the Lord and nothing else because only by discharging devotional service in transcendental love can one approach the Lord. Such penance is the internal potency of the Lord and is nondifferent from Him. Such acts of internal potency are exhibited by nonattachment for material enjoyment. The living entities are encaged in the conditions of material bondage because of their propensity for overlordship. But by engagement in the devotional service of the Lord one becomes detached from this enjoying spirit. The devotees automatically become detached from worldly enjoyment, and this detachment is the result of perfect knowledge. Therefore the penance of devotional service includes knowledge and detachment, and that is the manifestation of the transcendental potency.
One cannot enjoy material, illusory prosperity if he desires to return home, back to Godhead. One who has no information of the transcendental bliss in the association of the Lord foolishly desires to enjoy this temporary material happiness. In the Caitanya-caritamrta it is said that if someone sincerely wants to see the Lord and at the same time wants to enjoy this material world, he is considered to be a fool only. One who wants to remain here in the material world for material enjoyment has no business entering into the eternal kingdom of God. The Lord favors such a foolish devotee by snatching all that he may possess in the material world. If such a foolish devotee of the Lord tries to recoup his position, then the merciful Lord again snatches away all that he may have possessed. By such repeated failures in material prosperity he becomes very unpopular with his family members and friends. In the material world the family members and friends honor persons who are very successful in accumulating wealth by any means. The foolish devotee of the Lord is thus put into forcible penance by the grace of the Lord, and at the end the devotee becomes perfectly happy, being engaged in the service of the Lord. Therefore penance in devotional service of the Lord, either by voluntary submission or by being forced by the Lord, is necessary for attaining perfection, and thus such penance is the internal potency of the Lord.
One cannot, however, be engaged in the penance of devotional service without being completely free from all sins. As stated in the Bhagavad-gita, only a person who is completely free from all reactions of sins can engage himself in the worship of the Lord. Brahmaji was sinless, and therefore he faithfully discharged the advice of the Lord, “tapa, tapa,” and the Lord, being satisfied with him, awarded him the desired result. Therefore only love and penance combined can please the Lord, and thus one is able to attain His complete mercy. He directs the sinless, and the sinless devotee attains the highest perfection of life.
Srimad Bhagavatam Canto 02, Chapter 09, Text 22
Srimad Bhagavatam Canto 02, Chapter 09, Text 24