Qin Hui
This is a derivative of an episode from The Story of Yue Fei, which mentions no "sweeping" at all. The fortuneteller's name was "Xie Renfu of Chengdu" and he told the fortunes of both Emperor Gaozong and Qin Hui, who were in disguise, in the "Dragon's Intonation Monastery". When Qin returned to the palace, he sent men to arrest the fortuneteller, but he had already fled the city, out of fear once he discovered who they really were.