Musannaf Ibn Abi Shayba 37:256

Husayn ibn ‘Ali narrated to us, from Ibn ‘Uyaynah, from Ibn Tawus, from his father, who said: Ibn ‘Abbas said: Husayn came to me to consult me regarding leaving for this place—meaning Iraq. I said: "Were it not that it would bring disgrace upon me and you, I would have gripped your hair. Where are you going? To a people who killed your father and stabbed your brother?" What made me reconcile myself to his departure was that he said to me: "Indeed, this sanctuary will be violated by a man, and for me to be killed in such-and-such a land is more beloved to me than that I should be the one who violates it."