 In summer 626, when Li Shimin decided to act against Li Jiancheng and Li Yuanji, however, he summoned Fang and Du to his mansion.Fang and Du, initially fearing Emperor Gaozu's orders forbidding them to serve Li Shimin, declined.In anger, Li Shimin sent the general Yuchi Gong to summon Fang and Du, with directions if they declined again, to kill them.