Suetonius, The Deified Augustus 66
Neque enim temere ex omni numero in amicitia eius afflicti reperientur praeter Saluidienum Rufum, quem ad consulatum usque, et Cornelium Gallum, quem ad praefecturam Aegypti, ex infima utrumque fortuna prouexerat. Quorum alterum res nouas molientem damnandum senatui tradidit, alteri ob ingratum et maliuolum animum domo et prouinciis suis interdixit. Sed Gallo quoque et accusatorum denuntiationibus et senatus consultis ad necem conpulso laudauit quidem pietatem tanto opere pro se indignantium, ceterum et inlacrimauit et uicem suam conquestus est, quod sibi soli non liceret amicis, quatenus uellet, irasci.
Indeed, it would be hard to name any of his [Augustus’] numerous friends who fell from favour, apart from Salvidienus Rufus, whom he had advanced to the consulship, and Cornelius Gallus, whom he had granted the prefecture of Egypt, in both cases raising them from the lowest station. The former he handed over to the senate to be condemned to death, because he was plotting revolution; the latter he barred from the palace and the imperial provinces because of his ungrateful and malevolent character. But when Gallus too was condemned to death through the allegations of his accusers and the decrees of the senate, though he commended the loyalty of those who had voiced such indignation on his behalf, even so Augustus wept and lamented his own plight, because he alone could not be as angry with his friends as he wanted.