When Joseph reveals himself to his brothers, he sends them back, with the following injunction:
Now, do not be distressed or reproach yourselves because you sold me hither; it was to save life that God sent me ahead of you.
The word for “distressed” (ֽתְעַצְּבוּ֙) is quite rare in the Torah. It only appears in Genesis, and then only a few times (it is the same word for the pain Eve is cursed with in childbirth, and the pain Adam will have working the soil).
But I think Joseph had something specific in mind. When their sister, Dina, was raped, the Torah describes it as follows:
Meanwhile Jacob’s sons, having heard the news, came in from the field. The men were distressed and very angry, because he had committed an outrage in Israel by lying with Jacob’s daughter—a thing not to be done.
What did they do with their “distress” that first time? They murdered everyone in the city of Shechem.
Joseph knew quite well that his brothers were capable of cunning and brutal acts of violence when they got riled up. So Joseph is telling them, quite specifically, to stay calm, and avoid becoming distressed. Because we all know how the brothers handled being in that mental state!
[an @iwe and @blessedblacksmith piece]