The Lives of the Twelve Caesars
Suetonius
Augustus
XXI. In part as leader, and in part with armies serving under his auspices, he subdued Cantabria, Aquitania, Pannonia, Dalmatia, and all Illyricum, as well as Raetia and the Vindelici and Salassi, which are Alpine tribes. He also put a stop to the inroads of the Dacians, slaying great numbers of them, together with three of their leaders, and forced the Germans back to the farther side of the river Albis, with the exception of the Suebi and Sigambri, who submitted to him and were taken into Gaul and settled in lands near the Rhine. He reduced to submission other peoples, too, that were in a state of unrest. But he never made war on any nation without just and due cause, and he was so far from desiring to increase his dominion or his military glory at any cost, that he forced the chiefs of certain barbarians to take oath in the temple of Mars the Avenger that they would faithfully keep the peace for which they asked; in some cases, indeed, he tried exacting a new kind of hostages, namely women, realizing that the barbarians disregarded pledges secured by males; but all were given the privilege of reclaiming their hostages whenever they wished.
XL. ...When Tiberius requested citizenship for a Grecian dependent of his, Augustus wrote in reply that he would not grant it unless the man appeared in person and convinced him that he had reasonable grounds for the request; and when Livia asked it for a Gaul from a tributary province, he refused, offering instead freedom from tribute, and declaring that he would more willingly suffer a loss to his privy purse than the prostitution of the honour of Roman citizenship.
SOURCE
Suetonius, De Vita Caesarum, 2 Vols., trans. J. C. Rolfe (Cambridge, Mass.: Harvard University Press, 1920), pp. 123-287.
The Fordham U. Ancient History Sourcebook