Apollodorus Library 3.5.8

[8] Laius was buried by Damasistratus, king of Plataea, ¹ and Creon, son of Menoeceus, succeeded to the kingdom. In his reign a heavy calamity befell Thebes. For Hera sent the Sphinx, ² whose mother was Echidna and her father Typhon; and she had the face of a woman, the breast and feet and tail of a lion, and the wings of a bird. And having learned a riddle from the Muses, she sat on Mount Phicium, and propounded it to the Thebans. And the riddle was this:— What is that which has one voice and yet becomes four-footed and two-footed and three-footed? Now the Thebans were in possession of an oracle which declared that they should be rid of the Sphinx whenever they had read her riddle; so they often met and discussed the answer, and when they could not find it the Sphinx used to snatch away one of them and gobble him up. When many had perished, and last of all Creon's son Haemon, Creon made proclamation that to him who should read the riddle he would give both the kingdom and the wife of Laius. On hearing that, Oedipus found the solution, declaring that the riddle of the Sphinx referred to man; for as a babe he is four-footed, going on four limbs, as an adult he is two-footed, and as an old man he gets besides a third support in a staff. So the Sphinx threw herself from the citadel, and Oedipus both succeeded to the kingdom and unwittingly married his mother, and begat sons by her, Polynices and Eteocles, and daughters, Ismene and Antigone. ³ But some say the children were borne to him by Eurygania, daughter of Hyperphas. ⁴