Plutarch, Parallela minora
Goodwin, Ed.

Pelops the son of Tantalus and Euryanassa, had two children, Atreus and Thyestes, by his wife Hippodamia; and by the Nymph Danais he had Chrysippus, [p. 471] whom he loved better than his lawful children. But Laius the Theban in the heat of his lust forcibly abused his body; and being taken by Atreus and Thyestes, obtained his pardon from Pelops, in regard that love had provoked him to it. Hippodamia's advice to Atreus and Thyestes was, that they should kill Chrysippus, as one that would interpose between them and the crown. Upon their refusal to do so base a thing, she herself put her own hands to the work, and in the dead of the night took Laius's sword when he was asleep, wounded Chrysippus with it, and left the weapon in his body. This circumstance of Laius's sword brought him into suspicion of the murder, till he was cleared by Chrysippus himself, who, being as yet but half dead, gave his testimony to the truth. Pelops buried his son, and then banished his wife.—Dositheus, in his Pelopidae.

Ebius Toliex had two sons by his wife Nuceria, and a third called Firmus by an enfranchised woman, who was very handsome and better beloved by the father than those that were legitimate. Nuceria that hated this by-blow, advised her sons to despatch Firmus; but upon their refusal, she did it herself; and in the dead of the night got the sword of him that guarded the body of Firmus, gave him a mortal wound, and left the weapon sticking in his body. The boy cleared his keeper by a particular account of the matter of fact; the father buried his son, and sent away his wife into banishment.—Dositheus, Book Third of his Italian History.