Then by my father's grave -

MORANZONE

What grave? what grave?
Your noble father lieth in no grave,
I saw his dust strewn on the air, his ashes
Whirled through the windy streets like common straws
To plague a beggar's eyesight, and his head,
That gentle head, set on the prison spike,
For the vile rabble in their insolence
To shoot their tongues at.

GUIDO

Was it so indeed?
Then by my father's spotless memory,
And by the shameful manner of his death,
And by the base betrayal by his friend,
For these at least remain, by these I swear
I will not lay my hand upon his life
Until you bid me, then--God help his soul,
For he shall die as never dog died yet.
And now, the sign, what is it?

MORANZONE

This dagger, boy;
It was your father's.