《北史·列传·卷四》
当元法僧反叛以后，元树写信给公卿百官们，揭露元叉的罪恶，信中说 ：元叉本名为夜叉，他的弟弟元罗实名是罗刹。
及法僧反叛后，树遗公卿百寮书，暴叉过恶，言： 叉本名夜叉，弟罗实名罗刹。
After monk Yuanfa rebelled, Yuanshu wrote to all the civil and military officials, exposing Yuancha's crimes, saying in the letter: Yuancha's birth name was Yecha, and his younger brother Yuanluo's real name was Luocha.