The Captain's Oath was an oath for Starfleet captains which outlined the mission and objectives of a given starship in the United Federation of Planets. It is based on the speech given by Zefram Cochrane at the dedication ceremony of the Warp Five Complex in 2119. (ENT: "Broken Bow")
"Space: the final frontier. These are the voyages of the starship Enterprise. Her five-year mission: to explore strange new worlds. To seek out new life and new civilizations. To boldly go where no one has gone before."
The Captain's Oath is a revised version of the well known monologue by William Shatner's James T. Kirk from the title sequence of Star Trek: The Original Series. However, Kirk's recital of the Oath marks the first time that it appears as in-universe dialogue and not as a speech that is spoken to the audience.