Srimad Bhagavatam Canto 04, Chapter 20, Text 09

SB 4.20.9

yah sva-dharmena mam nityam
nirasih sraddhayanvitah
bhajate sanakais tasya
mano rajan prasidati
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
 
The Supreme Personality of Godhead, Lord Visnu, continued: My dear King Prthu, when one situated in his occupational duty engages in My loving service without motive for material gain, he gradually becomes very satisfied within.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
 
This verse is also confirmed by the Visnu Purana. Occupational duties are known as varnasrama-dharma and apply to the four divisions of material and spiritual life — namely brahmana, ksatriya, vaisya and sudra, and brahmacarya, grhastha, vanaprastha and sannyasa. If one works according to the varnasrama-dharma system and does not desire fruitive results, he gets satisfaction gradually. Discharging one’s occupational duty as a means of rendering devotional service unto the Supreme Personality of Godhead is the ultimate goal of life. Bhagavad-gita confirms this as the process of karma-yoga. In other words, we should act only for the satisfaction and service of the Lord; otherwise we will be entangled by the resultant actions.
 
Everyone is situated in his occupational duty, but the purpose of material occupations should not be material gain. Rather, everyone should offer the results of his occupational activities. A brahmana especially should execute his occupational duties not for material gain but to please the Supreme Personality of Godhead. The ksatriya, vaisya and sudra should work in a similar way. In this material world everyone is engaged in various professional and occupational duties, but the purpose of such activities should be to please the Supreme Personality of Godhead. Devotional service is very simple, and anyone can adopt it. Let one remain what he is; he need only install the Deity of the Supreme Lord in his house. The Deity may be Radha-Krsna or Laksmi-Narayana (there are many other forms of the Lord). In this way a brahmana, ksatriya, vaisya or sudra can worship the Deity with the results of his honest labor. Regardless of one’s occupational duty, one should adopt the devotional means of hearing, chanting, remembering, worshiping, offering everything to the Lord and engaging in His service. In this way one can very easily engage himself in the service of the Lord. When the Lord is pleased with one’s service, one’s mission in life is fulfilled.
Srimad Bhagavatam Canto 04, Chapter 20, Text 08
Srimad Bhagavatam Canto 04, Chapter 20, Text 10