《资治通鉴·唐纪·唐纪三》
当初，唐高祖作隋殿内少监，宇文士当隋尚辇奉御，高祖与他很要好。
初，上为隋殿内少监，宇文士及为尚辇奉御，上与之善。
In the past, when Emperor Gaozu had been a junior official in the Sui court, Yu Wenshi had been an Imperial Groom, so they were on good terms.