《资治通鉴·宋纪·宋纪九》
袁淑从太子刘劭那里回来后，反复琢磨。绕着床铺来回走动，直到四更才上床睡觉。
淑还省，绕床行，至四更乃寝。
After Yuan Shu returned from Crown Prince Liu Shao's, he pondered the problem. He circled the bed over and over, pacing back and forth until the fourth hour, then went to bed.