Ammianus Marcellinus, History 29.1.15-16
et quia fallere non minus videtur qui gesta praeterit sciens quam ille qui numquam facta fingit, non abnuimus – neque enim ambigitur – salutem Valentis et antea saepius per occultas coitiones, et tunc in extrema demersam, ferrumque ad iugulum eius prope adactum a militaribus, fato reflectente depulsum, quem lacrimosis in Thracia discriminibus destinarat. namque et in nemoroso quodam inter Antiochiam et Seleuciam loco leni quiete post meridiem consopitus, a Sallustio tunc scutario, et saepe alias adpetitus insidiantibus multis, vitae terminis a primigenio ortu adscriptis ausa inmania frenantibus evadebat.
And because one who knowingly passes over things that were done seems no less deceitful than one who makes up things that never happened, I do not deny – for there is no doubt – that the personal safety of Valens was plunged into the greatest danger, both at this time and on several previous occasions through secret conspiracies, and that a sword was very nearly thrust into his throat by the soldiers; it was turned away by the influence of Fate, which had destined him for lamentable crises in Thrace. For as he was quietly taking an afternoon nap in a wooded place between Antioch and Seleucia, he was attacked by Sallustius, who was at that time his armed guard, and he was often attacked on other occasions by many ambushers, but he escaped them because the limits of his life assigned to him at the moment of his birth reined in these monstrous acts of daring.