Listen to the recitation by Sukadev Bretz from Yoga Vidya Germany: Hatha Yoga Pradipika chapter two, 31st verse अथ त्राटकम् निरीक्षेन् निश्चलदृशा सूक्ष्मलक्ष्यं समाहितः । अश्रुसम्पातपर्यन्तम् आचार्यैस् त्राटकं स्मृतम् ॥३१॥ More information about this verse can be found at the Hatha Yoga Pradipika portal. Just go to HYP II 31. Recitation from Hatha Yoga Pradipika, recited by Sukadev Bretz from Yoga Vidya Ashram Germany.