《旧唐书·本纪·卷十》
皇上从二月身体不适，听说太上皇去世，悲哀不止，因此病势加剧。
上自仲春不豫，闻上皇登遐，不胜哀悸，因兹大渐。
Since February, His Majesty has not been feeling well, and when he heard of the death of the Supreme Emperor, he was unable to stop grieving, so his illness worsened.