To cite an oath in the body of your paper, place the relevant quote in quotation marks, followed by the author's last name in parentheses and the page number if one is available.
Example from Internet:
It is important for a doctor to "give no deadly medicine to any one if asked" (Hippocrates).
As with other texts -- if there is no page number -- you can eliminate the need for parentheses by mentioning the author in your own text.
Example: According to the Oath of Hippocrates, it is important for a doctor to "give no deadly medicine to any one if asked."
For your Works Cited page, you will need to follow one of these two formats.
For a printed oath:
Author last name, author first name. Name of the oath. Source the oath was in. Editor name(s). City of publication. Name of publisher, year of publication, page number(s) of cited work.
Hippocrates. Oath of Hippocrates. The Hippocratic Oath and the Ethics of Medicine. Ed. Steve Miles. New York: Oxford University Press, 2004, xiii-xiv.
For an Internet source:
Author last name, author first name. Name of the oath. Name of site the oath is published on. Date the oath was published on site, if available. n. pag. Web. Date you accessed the oath.
Hippocrates. Oath of Hippocrates. Classics.net. 21 Nov. 2003. n. pag. Web. 16 July 2013.