Patanjali Yoga Sutra 3.21

Sanskrit Sutra

कायरूपसंयमात्तद्ग्राह्यशक्ति-स्तम्भे चक्षुःप्रकाशासंप्रयोगेऽन्तर्धानम्॥२१॥

Swami Vivekananda's translation

By making Samyama on the form of the body, the perceptibility of the form being obstructed and the power of manifestation in the eye being separated, the Yogi’s body becomes unseen.

Chapter link: Yoga Sutra Chapter 3