Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 19

Sanskrit:

शुश्रूषणं द्विजगवां देवानां चाप्यमायया ।तत्र लब्धेन सन्तोष: शूद्रप्रकृतयस्त्विमा: ॥ १९ ॥

ITRANS:

śuśrūṣaṇaṁ dvija-gavāṁdevānāṁ cāpy amāyayātatra labdhena santoṣaḥśūdra-prakṛtayas tv imāḥ

Translation:

Service without duplicity to the brāhmaṇas, cows, demigods and other worshipable personalities, and complete satisfaction with whatever income is obtained in such service, are the natural qualities of śūdras.

Purport:

When the entire social order is functioning properly according to Vedic standards, everyone is happy and satisfied. Although the śūdras are to be satisfied with whatever income they obtain through their service, they never lack the necessities of life, because the other orders of society, such as kṣatriyas and vaiśyas, are required to be abundantly generous, and the brāhmaṇas are well known for being the most merciful of all. Therefore, if all social classes obey the Vedic injunctions there will be a new and blissful life for the entire human society under the guidance of Kṛṣṇa consciousness.