《资治通鉴·唐纪·唐纪七》
癸未，颉利可汗前进到渭水便桥的北岸，派遣他的亲信执失思力入京晋见太宗，以便观察唐的情况。
癸未，颉利可汗进至渭水便桥之北，遣其腹心执失思力入见，以观虚实。
On Kuiwei day, Jieli Khan advanced to the north bank of the Wei Shui Bianqiao, sending his trusted Zhishi Sili into the capital to meet with Taizong, so as to observe the Tang situation.