This is the prayer recited at the end of my yoga classes. It comes from my teacher, and his, going back to the Rig Veda. Feel free to join in or just stay with your breath and let it soothe your being.
Om Trayambakam Yajamahe
Sugandhim Pushtivardhanam
Urvarukamiva Bandhanan
Mrityor Muskshiya Mamritat
(x3)
Om Shanti Shanti Shanti
Here is a modern translation:
We bow in gratitude to Shiva, the Lord of Yoga,
who is fragrant and who nourishes well all beings;
may He liberate us from death for the sake of immortality.
Om Peace Peace Peace
Here are the phonetics to help to recite it:
Om Treeam-bhakaam-Yajaa-mahae
Soogandimpush-tivaardhanaam
Oorvaa-rookamivaBandhanaan
Mritior-Mooksheeya-Maamritat
Om Shanti Shanti Shanti
An lastly here is a YouTube video!