Srimad Bhagavatam Canto 11, Chapter 17, Text 42

SB 11.17.42

brahmanasya hi deho ’yam
 ksudra-kamaya nesyate
krcchraya tapase ceha
 pretyananta-sukhaya ca
The body of a brahmana is not intended to enjoy insignificant material sense gratification; rather, by accepting difficult austerities in his life, a brahmana will enjoy unlimited happiness after death.
One may ask why a brahmana should voluntarily accept inconvenience in keeping his body and soul together. In this verse the Lord explains that advanced human life is meant for serious austerity and not for insignificant sense gratification. By spiritual advancement one is fixed in transcendental bliss on the spiritual platform and gives up useless absorption in the temporary material body. One should remain detached from the material body, accepting only the bare necessities of life. The brahmanas, by accepting a troublesome form of livelihood, never forget that the material body is destined to grow old, become diseased and die in misery. Thus remaining alert and transcendental, an advanced brahmana, at the end of this life, goes back home, back to Godhead, where he enjoys unlimited spiritual bliss. Without such higher awareness, how can one be considered a qualified brahmana?
Those devotees engaged twenty-four hours a day in spreading the mission of Lord Krsna are beyond the platform of renunciation or sense gratification because they engage everything in Lord Krsna’s service. A pure devotee of the Lord eats only to get strength for serving the Lord and does not accept either sumptuous or meager food simply for the body’s sake. However, everything may be accepted for the Lord, even sumptuous meals. A brahmana who is not working day and night to spread the glories of the Lord should feel embarrassed to eat sumptuously for his personal sense gratification, but a renounced Vaisnava preacher may accept invitations from all classes of pious people, and just to bless their homes he will eat the opulent foods they offer to him. Similarly, he sometimes eats sumptuously to get strength for defeating atheists and impersonalists. As stated in Vedic literature, one cannot be a highly qualified brahmana unless one becomes a devotee of the Lord. And among the devotees, those who are preaching Krsna consciousness are the best, as confirmed by the Lord Himself in the Eighteenth Chapter of Bhagavad-gita.
Srimad Bhagavatam Canto 11, Chapter 17, Text 41
Srimad Bhagavatam Canto 11, Chapter 17, Text 43