Plutarch Eumenes 12

[1] But presently, as the siege dragged along, Antigonus learned that Antipater had died in Macedonia, ¹ and that matters were in confusion owing to the dissension between Cassander and Polysperchon. He therefore cherished no longer an inferior hope, but embraced the whole empire in his scheme, and desired to have Eumenes as friend and helper in his undertakings. Accordingly, he sent Hieronymus to make a treaty with Eumenes, and proposed an oath for him to take. This oath Eumenes corrected and then submitted it to the Macedonians who were besieging him, requesting them to decide which was the juster form.

[2] Antigonus, namely, for form’s sake, had mentioned the kings ² at the beginning of the oath, and then had made the rest of it refer to himself; but Eumenes wrote at the head of the oath the names of Olympias and the kings, and proposed to swear fealty, not to Antigonus alone, but also to Olympias and the kings, and to have the same enemies and friends as they. This was thought to be more just, and the Macedonians accordingly administered this oath to Eumenes, raised the siege, and sent to Antigonus, that he too, on his part, might take the oath to Eumenes.

[3]
  Meanwhile, however, Eumenes gave back all the Cappadocian hostages whom he was holding in Nora, and received from those who came for them horses, beasts of burden, and tents. He also collected all the soldiers who had become scattered by his flight and were now wandering about the country, so that he had a force of almost a thousand horsemen. With these he set out in flight, being rightly in fear of Antigonus. For Antigonus not only ordered his Macedonians to wall him in again and besiege him, but also wrote back bitter reproaches to them for accepting the correction of the oath.