Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[29] Reubel said these and many other things, and used entreaties to them, and thereby endeavored to divert them from the murder of their brother. But when he saw that his discourse had not mollified them at all, and that they made haste to do the fact, he advised them to alleviate the wickedness they were going about, in the manner of taking Joseph off; for as he had exhorted them first, when they were going to revenge themselves, to be dissuaded from doing it; so, since the sentence for killing their brother had prevailed, he said that they would not, however, be so grossly guilty, if they would be persuaded to follow his present advice, which would include what they were so eager about, but was not so very bad, but, in the distress they were in, of a lighter nature. He begged of them, therefore, not to kill their brother with their own hands, but to cast him into the pit that was hard by, and so to let him die; by which they would gain so much, that they would not defile their own hands with his blood. To this the young men readily agreed; so Reubel took the lad and tied him to a cord, and let him down gently into the pit, for it had no water at all in it; who, when he had done this, went his way to seek for such pasturage as was fit for feeding his flocks.