Verse
मनः प्रसादः सौम्यत्वं मौनमात्मविनिग्रहः ।भावसंशुद्धिरित्येतत् तपो मानसमुच्यते ॥
A clear and calm gladness of mind, gentleness, silence, self-control, the purifying of the whole temperament - this is called the askesis of the mind.
Gītā 17·16