BG 17.16

And satisfaction, simplicity, gravity, self-control and purification of one’s existence are the austerities of the mind.

17.16. The serenity of mind, the ietness, the taciturnity, the self-control, the purity of thought-all this is called mental austerity.

17.16 Serenity, kindness, silence, self-control and purity - this is austerity of mind.

17.14-16 Deva - etc. upto manasam ucyate : Honesty : uprightness, i.e., the courage regarding what needs no hiding. Which is true : This is explained by 'Which is pleasant and beneficial'. Pleasant : at the time of [hearing] that speech. And beneficial : something in future. This type of speech, but not merely speaking what actually happened, is called 'speaking the truth'. Purity of thought : 'Thought' denotes intention; its highest purity.

17.16 Serenity of mind, viz., absence of wrath etc., practice of benevolence, viz., the direction of the mind for the good of others, silence, viz., contorl of speech by the mind; self-control, viz., focusing the activity of the mind on the object of contemplation; purity of mind, viz., absence of thought about subjects other than the self - these constitute the austerity of the mind.

17.16 Manah-prasadah, tranillity of mind, making the mind free from anxiety; saumyatvam, gentleness-that which is called kindliness of spirit, [Kindliness towards all, and also not entertaining any evil thought towards anybody.] a certain condition of the mind resulting in calmness of the face, etc.; maunam, reticence-since even the control of speech follows from the control of mind, therefore the cause is implied by the effect; so maunam means control of the mind; [Or, maunam may mean thinking of the Self, the attitude of a meditator. The context being of 'mental austerity', reticence is explained as control of the mind with regard to speech.] atma-vinigrahah, withdrawal of the mind-withdrawal of the mind in a general way, from everything; maunam (control of the mind) is the mind's withdrawal with regard to speech alone; this is the distinction-; bhava-samsuddhih, purity of heart, absence of trickery while dealing with others; iti etat, these are; what is ucyate, called; manasam, mental; tapah, austerity. How the above-described bodily, verbal and mental austerities undertaken by poeple are divided into three classes-of sattva etc.-is being stated:

17.16 Serenity of mind, benevolence, silence, self-control, purity of mind - these are called austerity of the mind.

17.16 Tranillity of mind, gentleness, reticence, withdrawal of the mind, purity of heart,-these are what is called mental austerity.