sudrasya sannatih saucam
seva svaminy amayaya
amantra-yajno hy asteyam
sudrasya—of the sudra (the fourth grade of man in society, the worker); sannatih—obedience to the higher classes (the brahmanas, ksatriyas and vaisyas); saucam—cleanliness; seva—service; svamini—to the master who maintains him; amayaya—without duplicity; amantra-yajnah—performance of sacrifices simply by offering obeisances (without mantras); hi—certainly; asteyam—practicing not to steal; satyam—truthfulness; go—cows; vipra—brahmanas; raksanam—protecting.
Offering obeisances to the higher sections of society [the brahmanas, ksatriyas and vaisyas], being always very clean, being free from duplicity, serving one’s master, performing sacrifices without uttering mantras, not stealing, always speaking the truth and giving all protection to the cows and brahmanas—these are the symptoms of the sudra.
It is everyone’s experience that workers or servants are generally accustomed to stealing. A first-class servant is one who does not steal. Here it is recommended that a first-class sudra must remain very clean, must not steal or speak lies, and must always render service to his master. A sudra may attend sacrifices and Vedic ritualistic ceremonies along with his master, but he should not utter the mantras, for these may be uttered only by the members of the higher sections of society. Unless one is completely pure and has been raised to the standard of a brahmana, ksatriya or vaisya—in other words, unless one is dvija, twice-born—the chanting of mantras will not be fruitful.
Link to this page: https://prabhupadabooks.com/sb/7/11/24