During the Warring States period, Wei Fan Ju accompanied Xu Jia on a diplomatic mission to Qi, where he received respectful treatment from Qi's prime minister. However, Xu Jia became jealous and slandered Fan Ju to Wei's prime minister. The prime minister ordered a severe beating of Fan Ju and abandoned him in the wilderness. After recovering, Fan Su was brought back by Qin envoy Wang Ji, and he adopted the name Zhang Lu. King Zhaoxiang of Qin appointed him as a prime minister. Later, Xu Jia was sent on a mission to Qin, and Fan Su disguised himself as a poor man to meet him. Coincidentally, there was heavy snowfall, and Xu Jia pitied the old friend's coldness, giving him a padded coat. The next day, Xu Jia met Qin's prime minister, Zhang Lu, and realized that it was actually Fan Su. He was greatly alarmed, but Fan Su remembered the gift of the coat and forgave Xu Jia's transgression.
