《旧五代史·后晋·少帝纪四》
此前，前年御驾到达黄河岸边，曾派边将送信给幽州赵延寿，劝他回归晋国，赵延寿立即有回信，模棱两可。
先是，前岁中车驾驻于河上，曾遣边将遗书于幽州赵延寿，劝令归国，延寿寻有报命，依违而已。
Before this, when the imperial carriage reached the banks of the Yellow River the year before last, it had sent a frontier general to send a letter to Zhao Yanshou of Youzhou, urging him to return to the Jin state. Zhao Yanshou immediately replied with an ambiguous letter.