As mentioned above in descriptive historical data like that of "Tale of Heiji," one theory is that his complaining about the differences in how the accomplishments of Yoshitomo and Kiyomori were rewarded was a cause of the fateful confrontation between the Minamoto clan and the Taira clan.
先に触れたような『平治物語』の記述を史料に、保元の乱での平清盛との恩賞の格差に義朝が不満を抱いたという源氏対平家の因縁説。