Traditionally the Invocation to Patañjali (author of the yoga sūtras) is chanted at the beginning of Iyengar yoga classes or practice.
YOGENA CITTASYA PADENA VĀCĀM
MALAM ŚARĪRASYA CA VAIDYAKENA
YOPĀKAROTTAM PRAVARAM MUNĪNĀM
PATAÑJALIM PRĀÑJALIR ĀNATO’SMI
ŚANKHA CAKRĀSI DHĀRINAM
SAHASRA ŚIRASAM ŚVETAM
Let us bow before the noblest of sages Patanjali, who gave yoga for serenity and sanctity of mind, grammar for clarity and purity of speech and medicine for perfection of health.
Let us prostrate before Patanjali, an incarnation of Adisesa, whose upper body has a human form, whose arms hold a conch and a disc, and who is crowned by a thousand-headed cobra.
The Invocation to Patañjali can be preceded by invocation to Ganesha (as in the above recording).
VAKRA TUNDA MAHĀ KĀYA
SŪRYA KOTI SAMAPRABHA
NIRVIGHNAM KURU ME DEVA
ŚUBHA KĀRYESU SARVADA
O, Lord Ganeśa of the curved trunk and massive body, the one whose splendor is equal to millions of Suns, please bless me that I do not face any obstacles in my auspicious karma.