maunam atma-vinigrahah

bhava-samsuddhir ity etat

tapo manasam ucyate

manaḥ-prasādaḥ—satisfaction of the mind; saumyatvam—without duplicity towards others; maunam—gravity; ātma—self; vinigrahaḥ—control; bhāva—nature; saṁśuddhiḥ—purification; iti—thus; etat—that is; tapaḥ—austerity; mānasam—of the mind; ucyate—is said to be.

And serenity, simplicity, gravity, self-control and purity of thought are the austerities of the mind.

tapas tat tri-vidham naraih

aphalakanksibhir yuktaih

sattvikam paricaksate

śraddhayā—with faith; parayā—transcendental; taptam—executed; tapaḥ—austerity; tat—that; tri-vidham—three kinds; naraiḥ—by men; aphala-ākāṅkṣibhiḥ—without desires for fruits; yuktaiḥ—engaged; sāttvikam—in the mode of goodness; pari-cakṣate—is called.

This threefold austerity, practiced by men whose aim is not to benefit themselves materially but to please the Supreme, is of the nature of goodness.