《资治通鉴·隋纪·隋纪三》
文帝已经多次听到对杨勇的诬陷诋毁，怀疑朝臣们都知道了，因此向朝臣们发问，希望听到太子的过失。
上既数闻谮毁，疑朝臣悉知之，故于众中发问，冀闻太子之过。
Emperor Wen had heard many slanderous accusations against Yang Yong, and he suspected that all of his ministers knew about it. Therefore, he asked his ministers, in the hope that he would hear about the crown prince’s mistakes.