Yoga Sūtra Chapter Three verse 21
कायरूपसंयमात् तत्ग्राह्यशक्तिस्तम्भे चक्षुः प्रकाशासंप्रयोगेऽन्तर्धानम् ॥२१॥
kāya-rūpa-saṃyamāt-tat-grāhya-śakti-stambhe cakṣuḥ prakāśa-asaṃprayoge-antar-dhānam ||21||
From complete restraint on form of body dissappearance;
kāya - the bodyrūpa - any outward appearance or phenomenon or colour; form, shape, figure; aggregate; ‘formed or composed of’, ‘consisting of’saṃyama - complete restrainttat - that, thisgrāhya - that which is graspedśakti - power, energy; ability, capability; strength; might, effort;stambha - suspension; stoppage, obstruction, suppressioncakṣus - sense of seeing; eyeprakāśa - clearness, brightness, splendour, lustre, light; visible, shining, brightasaṃprayoga - disengagementantardhāna - disappearance
that suspension of the power of what is to be grasped
is disengagement of the eye and light.