Sudras, persons in the mode of ignorance, are generally in deep illusion about the purpose of life, accepting the gross material body as the self. Those in passion and ignorance are called vaisyas and hanker intensely for wealth, whereas ksatriyas, who are in the mode of passion, are eager for prestige and power. Those in the mode of goodness, however, hanker after perfect knowledge; they are therefore called brahmanas.

Srimad Bhagvatam 11.25.21

That action which is regulated and which is performed without attachment, without love or hatred, and without desire for fruitive results is said to be in the mode of goodness.

Bhagavad Gita 18.23