Philo Judaeus De Josepho 14

[14] And they were very near incurring that most excessive pollution of fratricide, as they would have done if they had not been, though with difficulty, persuaded by the advice of their eldest brother, who counselled them not to meddle with such a pollution but merely to cast him into one of these pits, thinking then to contrive some means of saving him, so that when they had all departed he might send him back again to his father without having suffered any harm. And after they agreed to this he came forward and saluted them; and they took him as though he had been an enemy, and stripped him of all his garments, and let him down into a vast pit, and then, having stained his cloak with the blood of a kid, they sent it to their father on the pretence that he had been slain by a wild beast.