Shakespeare, Ben Jonson, Beaumont and Fletcher
Chapter 80
“Will take his oath o’ the Greek _Xenophon_, If need be, in his pocket.”
Another reading is “Testament.”
Probably, the meaning is—that intending to give false evidence, he carried a Greek _Xenophon_ to pass it off for a Greek Testament, and so avoid perjury—as the Irish do, by contriving to kiss their thumb-nails instead of the book.