《资治通鉴·汉纪·汉纪十八》
汉宣帝下诏命公卿大臣商议此事。大鸿胪萧望之认为： 乌孙在极为遥远的地方，难保不发生变故，不能答应。 
诏下公卿议，大鸿胪萧望之以为： 乌孙绝域，变故难保，不可许。 
Emperor Xuan ordered the high-ranking officials to discuss this matter. Xiao Wangzhi, the Grand Master of Ceremonies believed: Wusun is located extremely far away, and it is hard to guarantee that things will not change. We cannot agree to this.