《太平广记·卷二百零二·儒行（怜》
第二天聚宴，监军在宴席上说： 我有件事想与尚书你约定，一经约定你我都不能违背它。 张建封说： 可以。 
明日置宴，监军曰：某有与尚书约，彼此不得相违。建封曰：唯。
The next day, at a banquet, the military supervisor said at the banquet, "I have a matter I wish to discuss with you, the minister. Once we agree, neither of us may break it.” Zhang Jianfeng said, "Yes."