I asked the same exact question when we were asked during PST if we wanted to take it as I'd never heard of it before...
Here it is:
I <first, last name> promise to serve alongside the people of <Country of Service>.
I promise to share my culture with an open heart and open mind.
I promise to foster an understanding of the people of <Country of Service>, with creativity, cultural sensitivity, and respect.
I will face the challenges of service with patience, humility, and determination.
I will embrace the mission of world peace and friendship for as long as I serve and beyond.
In the proud tradition of Peace Corpsí legacy, and in the spirit of the Peace Corps family past, present, and future -
I am a Peace Corps Volunteer.