Yoga Sutras of Patanjali · 1.13
तत्र स्थितौ यत्नोऽभ्यासः ॥१३॥
tatra sthitau yatno 'bhyāsaḥ
Practice is the effort to stay in stillness.
— Yoga Sutras of Patanjali 1.13
Source: Sanskrit attributed to Patanjali (c. 2nd century BCE – 4th century CE). Public-domain English readings drawn from Swami Vivekananda's 'Raja Yoga' (1896) and Charles Johnston's 'The Yoga Sutras of Patanjali' (1912).