HORATIO: There's no offence, my lord.
HAMLET: Yes, by Saint Patrick, but there is, Horatio,
And much offence too. Touching this vision here,
It is an honest ghost, that let me tell you.
For your desire to know what is between us,
O'ermaster't as you may. And now, good friends, 
As you are friends, scholars, and soldiers,
Give me one poor request.
HORATIO: What is't, my lord, we will.
HAMLET: Never make known what you have seen tonight.
HORATIO, MARCELLUS: My lord, we will not. 
HAMLET: Nay, but swear't.
HORATIO: In faith,
My lord, not I.
MARCELLUS: Nor I, my lord, in faith.
HAMLET: Upon my sword.
MARCELLUS: We have sworn, my lord, already.
HAMLET: Indeed upon my sword, indeed.