Yōga Sūtra 2.32

शौचसन्तोषतपःस्वाध्यायेश्वरप्रणिधानानि नियमाः।

śaucasantōṣatapaḥsvādhyāyēśvarapraṇidhānāni niyamāḥ।

[शौच सन्तोष तपः स्वाध्याय इश्वर प्रणिधानानि नियमाः।
śauca = cleanliness; santōṣa = contentment; tapaḥ = austerity; svādhyāya = self-study; iśvara = Īshwara; praṇidhānāni = submission to; niyamāḥ = are the rules;]

Cleanliness, contentment, austerity, self-study, and surrender to Īswara are the rules (Niyama).