BG Chap 17 - Three ways of austerity
In order to explain austerity in the three modes, Kṛṣṇa first speaks of the three types of austerity – of body, words and mind. Austerity of the body consists of worship of the devas such as Vasu and Rudra; of the dvijas, the best among the brāhmaṇas; of the gurus, such as mother, father and teacher; and of the learned, who know the Vedas. The sequence is from superior to inferior. Austerity of the body also consists of cleanliness, both internal and external; sincerity in carrying out what is prescribed, and avoid what is forbidden; celibacy, which is sex life according to scriptural injunctions; and non violence.
Austerity of speech is speech which does not disturb others or which cause fear in others; which is true and based on authoritative sources; which is pleasing and beneficial to the hearer; and as well as regularly reciting the Vedas.
Austerity of the mind consists of tranquility, without getting agitated from remembrance of sense objects; without cruelty, desiring everyone’s happiness; gravity or silence, which means to always think of self realization; controlling the mind by withdrawing it from sense objects; and non duplicity – free from deceit in dealings with others.