SB 7.11.21
samo damas tapah saucam
santosah ksantir arjavam
jñanam dayacyutatmatvam
satyam ca brahma-laksanam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The symptoms of a brahmana are control of the mind, control of the senses, austerity and penance, cleanliness, satisfaction, forgiveness, simplicity, knowledge, mercy, truthfulness, and complete surrender to the Supreme Personality of Godhead.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In the institution of varnasrama-dharma, the symptoms of a brahmana, ksatriya, vaisya, sudra, brahmacari, grhastha, vanaprastha, and sannyasi are all described. The ultimate aim is acyutatmatvam — to think always of the Supreme Personality of Godhead, Krsna, or Visnu. To make advancement in Krsna consciousness, one has to become a brahmana, with the above-mentioned symptoms.