मन: प्रसाद: सौम्यत्वं मौनमात्मविनिग्रह: | भावसंशुद्धिरित्येतत्तपो मानसमुच्यते ॥16॥
manaḥ-prasādaḥ saumyatvaṁ maunam ātma-vinigrahaḥ bhāva-sanśhuddhir ity etat tapo mānasam uchyate
manaḥ-prasādaḥ—serenity of thought; saumyatvam—gentleness; maunam—silence; ātma-vinigrahaḥ—self-control; bhāva-sanśhuddhiḥ—purity of purpose; iti—thus; etat—these; tapaḥ—austerity; mānasam—of the mind; uchyate—are declared as
Tranquillity of mind, gentleness, reticence, withdrawal of the mind, purity of heart, -these are what is called mental austerity.