Ammianus Marcellinus Res Gestae 15.5.19

[19] So the man who shortly before with malicious slander was called the maelstrom of the East and a seeker after acquisition of imperial power through his sons, then became a most politic leader and mighty fellow-soldier of Constantine’s, and the only person to extinguish the fire; but he was really being attacked under motives honourable, to be sure, but yet insidious. For great care was being taken that Silvanus should be destroyed as a very brave rebel; or, if that should fail, that Ursicinus, already deeply gangrened, should be utterly annihilated, in order that a rock ¹ so greatly to be dreaded should not be left.