सत्त्वशुद्धिः सौमनस्यैकाग्र्येन्द्रियजयाअत्मदर्शन योग्यत्वानि च ॥४१॥
sattva-śuddhiḥ saumanasya-ikāgry-endriyajaya-ātmadarśana yogyatvāni ca ॥41॥

Yoga Sūtra 2.41 expands upon the practice of saucha in thoughts and in deeds.