The pasuk (Bereishis 43:23) states:" And he said, Peace to you; fear not. Your G-d and the G-d of your father gave you a treasure in your sacks."
The author of Sefer Shevet Hamussar zy"a asks (in his Sefer Megaleh Tzfonos, Parshas Mikeitz) why the man appointed over Yosef's house began his words by wishing his brothers peace. He answers by quoting the statement of Chazal (Uktzin 3:12): “Hashem didn't find a vessel that could hold blessing for Yisroel other than peace." Accordingly, the man in charge of the house told them that the way to determine if finding the money in their sacks was good or bad was by seeing if they had shalom between them. If they did, then they did not need to fear because it certainly would be good because shalom can only lead to bracha.
