 Heba Yue sent his assistant Zhao Gui (趙貴) to Xia Province to request Yuwen's opinions, and Yuwen, believing that Houmochen was unreliable, advised against an attack on Cao and suggested instead that Houmochen be attacked.Heba refused—not realizing that by this point, Gao's messengers had persuaded Houmochen to act against him.Heba and Houmochen rendezvoused at Gaoping (高平, in modern Guyuan, Ningxia), and then headed north against Cao—but as they advanced, Houmochen tricked Heba into coming to his camp for discussions, and then had his son-in-law Yuan Hongjing (元洪景) assassinate Heba.