《资治通鉴·晋纪·晋纪二十四》
不如将兵力调至并州，控制西河，在南面使壶关得以坚固，在北面使晋阳得到加强，西边的敌人来犯，则可以抵御防守，路过，则可以断其后路，这也胜于保卫孤城戍守无用之地。 
不若移于并土，控制西河，南坚壶关，北重晋阳，西寇来则拒守，过则断后，犹愈于戌孤城守无用之地也。 
It would be better to move the troops to Bingzhou, control Xi River, strengthen Huguan in the south, and reinforce Jinyang in the north. If enemies come from the west, we can defend against them, and if they pass by, we can cut off their retreat. This is also better than defending a lonely city and guarding useless land.