The mother of Chancellor Jia, Lady of the Two Realms, had organised meals for mendicant Daoists, when suddenly a crowd of Daoist priests came supporting a pregnant woman who was about to give birth. Before the refectory could even pause, she gave birth to a baby on the ground. The crowd of priests then picked her up and departed, leaving the infant on the floor. When people picked the baby up, it turned out to be a bag of swords. They then realised that Duke Lü  was exercising his spirit to play jokes on common customs.
Anon., Huhai xinwen yijian xuzhi, 後1.130-31 (Tale 227):
賈平章母兩國夫人設雲水道人閒（明刻本、明抄本無「閒」宇。）齋，忽有羣道人扶一孕婦將產而來。齋未罷，產嬰兒在地，羣道人即扶女子而去，只留嬰兒在地。扶起嬰兒，乃一劍袋也。始知呂公  弄精魂以戲凡俗云。
Yuan Haowen 元好問, Chang Zhenguo 常振國 (ed), Xu Yijian zhi 續夷堅志 (Continued Records of the Listener), and Anon., Jin Xin 金心 (ed.), Huhai xinwen yijian xuzhi 湖海新聞夷堅續志 (Continuation of Records of the Listener with New Items from the Lakes and Seas) (Beijing: Zhonghua shuju, 1986).