《资治通鉴·唐纪·唐纪十三》
杜正伦多次劝谏李承乾都不听，杜正伦便将太宗对他讲的话告诉承乾。
正伦屡谏，不听，乃以上语告之。
Du Zhenglun repeatedly advised Li Chengqian, but Li Chengqian did not listen to him, so Du Zhenglun told Chengqian what Taizong had told him.