《太平广记·卷八十·方士五》
他让崔无斁在地上写字，崔便写了 北 和 千 两个分割开的字，然后把 千 字插入 北 字中间成了个 乖 字，说： 去了一定要乖觉，要见机行事。 
令崔书地作字，乃书北千两割字，崔公以千插北成乖字，曰： 去即乖觉。 
He had Cui Wuji write on the ground, and Cui wrote the separate characters “north” and “1,000.” He then put the character “1,000” in the middle of the character “north” to form the character “smart.” He said, “You must be sensible and observant if you go. You should take action according to the situation.”