וישנאו אותו ולא יכלו דברו לשלום (וישב לז:ד)

The Gemara says (ברכות סד) that when one bid farewell to a friend, he should say “לך לשלום” and not “לך בשלום”.  For example [le, when Yisro departed from Moshe, he said “לך לשלום,” and indeed he was successful.  Hence, when Dovid Hamelech departed from Avshalom, he said “לך בשלום,” and Avshalom ended up being hung by his long hair and was then killed.] This is alluded to in our passuk: since the brothers hated Yosef – ולא יכלו דברו לשלום, they did not tell him “לך לשלום” because they did not wish success upon him.