《新唐书·列传·卷一百四十九》
但怀恩为避嫌不肯去，皇帝赐给铁券，还亲自写诏书坚持要他去，这才启程。
怀恩避嫌不往，帝赐铁券，手诏固遣，乃行。
However, Fuguhuaien refused to go to avoid suspicion. The emperor bestowed an iron certificate and personally wrote an imperial edict to insist that he go, so he set off.