Srimad-Bhagavatam: Canto 7 - Chapter 1 - Verse 32

Sanskrit:

वृत्त्या स्वभावकृतया वर्तमान: स्वकर्मकृत् ।हित्वा स्वभावजं कर्म शनैर्निर्गुणतामियात् ॥ ३२ ॥

ITRANS:

vṛttyā sva-bhāva-kṛtayāvartamānaḥ sva-karma-kṛthitvā sva-bhāva-jaṁ karmaśanair nirguṇatām iyāt

Translation:

If one acts in his profession according to his position in the modes of nature and gradually gives up these activities, he attains the niṣkāma stage.

Purport:

If one gradually gives up his hereditary customs and duties and tries to serve the Supreme Personality of Godhead in his natural position, he is gradually able to become free from these activities, and he attains the stage of niṣkāma, freedom from material desires.