This specifically refers to brahmins in the third stage of life (after the student and householder stages) where one abandons social responsibilities and lives as an ascetic in the forest for one’s twilight years.

The third of the four life stages (āśrama) in the brahmanical tradition, which one enters after studying the Vedas and being a householder. A brahmin then sets off to the forest to devote himself fully to spiritual practice, still accompanied by his wife. The last stage is that of complete renunciation (saṃnyāsa).