In Shakespeare's The Taming of the Shrew, Tranio is masquerading as Lucentio, a suitor for the hand of Bianca. Tranio is actually Lucentio's servant, but Lucentio is pretending to be Cambio, a teacher for the women in Baptista's housea "job" he has taken to secretly woo Bianca. It appears that "Cambio" is making headway with Bianca, where no one else has been successful.
Hortensio, pretending to be a music teacher, has has enough of this charade. He first admits that he is not a teacher but a gentleman, and is seems obvious to him that Bianca prefers Cambio over him, which is disgusting to him as he is a gentleman and Cambio is a man of lower social standing than Hortensio: a commoner.
Tranio (in league with Cambio/Lucentio) commiserates with Hortensio, agreeing the he, too, is disgusted by this turn of events. He promises that if Hortensio foreswears any further attempt to pursue Bianca, that Tranio (pretending to be Lucentio) will take the same oath, swearing off anything more to do with Bianca, who has (at least to Hortensio) been a major disappointment. Hortensio says:
See, how they kiss and court! Signior Lucentio,
Here is my hand, and here I firmly vow
Never to woo her no more, but do forswear her,
As one unworthy all the former favours (30)
That I have fondly flatter'd her withal.
Lorcentio promises to marry a wealthy woman he has only know for a short while, and insisting that he will no longer give his love to a woman based upon her beauty, but based upon the kindness within her. Hortensio further explains:
Would all the world but he had quite forsworn! (35)
For me, that I may surely keep mine oath,
I will be married to a wealthy widow,
Ere three days pass, which hath as long loved me
As I have loved this proud disdainful haggard.
And so farewell, Signior Lucentio. (40)
Kindness in women, not their beauteous looks,
Shall win my love.
The oath the men take means nothing to Tarino: he is working with Lucentio, however Hortensio's oath further clears the way for Lucentio (pretending to be (Cambio) to pursue and win the favor of Bianca.