《资治通鉴·晋纪·晋纪三十四》
北魏国主拓跋的大军抵达永安，后秦义阳公姚平派遣骁将率领精壮的骑兵二百人前去侦察北魏军的虚实动静，长孙肥迎击他们，并把这些兵卒全部抓获。
魏主珪至永安，秦义阳公平遣骁将帅精骑二百觇魏军，长孙肥逆击，尽禽之。
Tuoba Tao, the supreme chief of the Northern Wei state, arrived in Yong'an, and Yao Ping, the Duke of Yiyang of Later Qin, dispatched capable generals to lead 200 valiant cavalrymen to reconnoiter the whereabouts of the Northern Wei army, while Changsun Fei fought against them and captured all those soldiers.