《明史·列传·卷四十九》
洪武、永乐年间，令出马匹供役于北方各驿站，前后有四百余匹，以三年为期遣还，到现在已经三十多年了。
洪、永间，令出马役于北方诸驿，前后四百余匹，期三岁遣还，今已三十余岁矣。
During the Hongwu and Yongle reign, horses were ordered to serve at various northern post stations; there were over four hundred in total, which were to be returned after three years; it has been over thirty years.