《资治通鉴·唐纪·唐纪十二》
当时太子修筑宫室，妨碍农事；又喜爱郑、卫等靡之音。于志宁反复劝谏，太子不听。
太子治宫室，妨农功；又好郑、卫之乐；志宁谏，不听。
At that time, the crown prince was building palaces and mansions, which was interfering with farming; he was also fond of music from the states of Zheng and Wei, which was indulgent and decadent. Yu Zhinin repeatedly advised him against these behaviors, but the crown prince refused to listen.