Histories

“Now, then,” she said to him, “what do you propose to do?” “Not to obey Astyages' instructions,” he answered, “not even if he should lose his mind and be more frantic than he is now: I will not lend myself to his plan or be an accessory to such a murder.

There are many reasons why I will not kill him: because the child is related to me, and because Astyages is old and has no male children.