Śrīmad-Bhāgavatam · Text 11.17.19
Who is speaking and story frame
शुश्रूषणं द्विजगवां देवानां चाप्यमायया ।
तत्र लब्धेन सन्तोष: शूद्रप्रकृतयस्त्विमा: ॥ १९ ॥
śuśrūṣaṇaṁ dvija-gavāṁ
devānāṁ cāpy amāyayā
tatra labdhena santoṣaḥ
śūdra-prakṛtayas tv imāḥ
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.
Read the purport on Vedabase.ioFrom Canto 10, chapter 14 onward, the translation and purports were completed by Śrīla Prabhupāda's disciples after his departure, and published by the Bhaktivedanta Book Trust.