Recitation of the thirteenth verse, first chapter of the Hatha Yoga Pradipika, the "Light of Hatha Yoga":
अल्पद्वारम् अरन्ध्रगर्तविवरं नात्युच्चनीचायतं
सम्यग्गोमयसान्द्रलिप्तम् अमलं निःशेसजन्तूज्झितम् ।
बाह्ये मण्डपवेदिकूपरुचिरं प्राकारसंवेष्टितं
प्रोक्तं योगमठस्य लक्षणम् इदं सिद्धैर् हठाभ्यासिभिः ॥१३॥
You can recite these Hatha Yoga Pradipika Shlokas before practising any Hatha Yoga. If you want to recite along or just read the Sanskrit text (Devanagari and Roman Script), just go to Hatha Yoga Pradipika Online Media Book. Hatha Yoga Pradipika is one of the four most important classical text on the theory and practice of Hatha Yoga.