In Act IV, scene III of "Julius Caesar," to prove Brutus has been wronged, what does Cassius tell Brutus to do to him?

Cassius tells Brutus to stab him. To be specific, he says, " There is my dagger,
And here my naked breast; within, a heart
Dearer than Plutus' mine, richer than gold:
If that thou be'st a Roman, take it forth;
I, that denied thee gold, will give my heart."

Cassius gives him the dagger and exposes his chest to be stabbed.