《资治通鉴·陈纪·陈纪二》
假设晋州方面调集军队，三天才能调齐，谋划商议对策，自然得费去两天，计算一下敌军的行军速度，两天是赶不到我们修城的地方的，等他们到来时，我们的城垣壕沟早修成了。 
设使晋州征兵，三日方集，谋议之间，自稽三日，计其军行，二日不到。我之隍防，足得办矣。 
Assuming that the Jinzhou forces can assemble their troops in three days, they will naturally spend two days planning and discussing countermeasures. Calculating the speed at which the enemy forces will march, they will not be able to reach our construction site in two days. By the time they arrive, our city walls and moats will have already been built.