Zheng Fan did not advise Tian Wujing to leave the army and return first. Although a Pixiu possessed far greater endurance and speed than the best warhorse, Tian Wujing was leading the army. It was naturally impossible for him to depart alone, even with his wife about to give birth. Proposing such a suggestion would, first, be an insult to Lord Jingnan. Second, it would be risking one's life to offer such flattery—flattery that could genuinely cost one's life.
