“I shall not talk to anyone” indicates that Viśvāmitra decided to practice silence [while meditating]. “I will not exhale” indicates that he would practice kumbhaka-yoga, for anger and so on take place because of exhaling.

NOTE. Śrīla Prabhupāda describes kumbhaka-yoga as follows: “This system of yoga for controlling the breathing process is called prāṇāyāma, and in the beginning it is practiced in the haṭha-yoga system through different sitting postures. All of these processes are recommended for controlling the senses and for advancement in spiritual realization. This practice involves controlling the airs within the body so as to reverse the directions of their passage. The apāna air goes downward, and the prāṇa air goes up. The prāṇāyāma-yogī practices breathing the opposite way until the currents are neutralized into pūraka, equilibrium. Offering the exhaled breath into the inhaled breath is called recaka. When both air currents are completely stopped, one is said to be in kumbhaka-yoga. By practice of kumbhaka-yoga, one can increase the duration of life for perfection in spiritual realization. The intelligent yogī is interested in attaining perfection in one life, without waiting for the next. For by practicing kumbhaka-yoga, the yogīs increase the duration of life by many, many years.” (Bhagavad-gītā 4.29 purport)