ACT III SCENE 3: What do you think Shylock means when he says, “it is my humour”?

SHYLOCK: I have possessed your grace of what I purpose, And by our holy Sabbath have I sworn To have the due and forfeit of my bond. If you deny it, let the danger light Upon your charter and your city’s freedom. You’ll ask me why I rather choose to have A weight of carrion flesh than to receive Three thousand ducats. I’ll not answer that But say it is my humour. Is it answered?