Apollodorus Library 3.6.1

[1]
  Now Eteocles and Polynices made a compact with each other concerning the kingdom and resolved that each should rule alternately for a year at a time. ¹ Some say that Polynices was the first to rule, and that after a year he handed over the kingdom to Eteocles; but some say that Eteocles was the first to rule, and would not hand over the kingdom. So, being banished from Thebes, Polynices came to Argos, taking with him the necklace and the robe. ² The king of Argos was Adrastus, son of Talaus; and Polynices went up to his palace by night and engaged in a fight with Tydeus, son of Oeneus, who had fled from Calydon. ³ At the sudden outcry Adrastus appeared and parted them, and remembering the words of a certain seer who told him to yoke his daughters in marriage to a boar and a lion, ⁴ he accepted them both as bridegrooms, because they had on their shields, the one the forepart of a boar, and the other the forepart of a lion. ⁵ And Tydeus married Deipyle, and Polynices married Argia ⁶ ; and Adrastus promised that he would restore them both to their native lands. And first he was eager to march against Thebes, and he mustered the chiefs.