In which episode did Wei Xiaobao and the Mongolian prince become sworn?

Wei Xiaobao ordered Shuang'er to change him into official robes, and took the Qing soldiers, Shuang'er and Ceng Rou to Li Chunyuan to capture Zheng Keshuang, but was captured by Gerdan who arrived. Wei Xiaobao deceived Mongolian princes Gerdan and Archie with his own intelligence, and became sworn brothers with Gerdan.

Wei Xiaobao, the hero of Jin Yong's martial arts novels.