Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 47

Sanskrit:

सीदन् विप्रो वणिग्वृत्त्या पण्यैरेवापदं तरेत् ।खड्‍गेन वापदाक्रान्तो न श्ववृत्त्या कथञ्चन ॥ ४७ ॥

ITRANS:

sīdan vipro vaṇig-vṛttyāpaṇyair evāpadaṁ taretkhaḍgena vāpadākrāntona śva-vṛttyā kathañcana

Translation:

If a brāhmaṇa cannot support himself through his regular duties and is thus suffering, he may adopt the occupation of a merchant and overcome his destitute condition by buying and selling material things. If he continues to suffer extreme poverty even as a merchant, then he may adopt the occupation of a kṣatriya, taking sword in hand. But he cannot in any circumstances become like a dog, accepting an ordinary master.

Purport:

Śva-vṛttyā, or “a dog’s profession,” refers to the śūdras, who cannot live without accepting a master. A destitute brāhmaṇa who is suffering intolerably may become a merchant and then a kṣatriya but may never take the position of a śūdra by working in a company or accepting a master. Although a kṣatriya is ordinarily considered more elevated than a vaiśya, the Lord here recommends that distressed brāhmaṇas first accept the vaiśya occupation, since it is not violent.