That was the 'Declaration of Prohibition on Establishing Trading Company' of January, 1920, and since then nobody had said about establishment of trading company as taboo until a actual trading company of Sumitomo was opened after the World War II.
これが大正9年（1920年）1月の「商社設立禁止宣言」であり、戦後、商社が開設されるまで、住友では商社開設が禁句になってしまった。