Yoga Sutras of Patanjali · 3.21

कायरूपसंयमात्तद्ग्राह्यशक्तिस्तम्भे चक्षुःप्रकाशासम्प्रयोगेऽन्तर्धानम्॥२१॥

kāyarūpa-saṁyamāt tad-grāhya-śakti-stambhe cakṣuḥ-prakāśa-asamprayoge antardhānam

By sanyama on the form of the body, when its power of being perceived is interrupted and the light of the eye no longer makes contact with it, invisibility arises.

— Yoga Sutras of Patanjali 3.21

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).