Joy of Life did not describe the plot of Yan Bingyun stabbing Fan Xian. This plot was added during the adaptation of the TV series. Therefore, there was no plot in Joy of Life where Yan Bingyun stabbed Fan Xian.

In Joy of Life, the plot where Yan Bingyun stabbed Fan Xian happened in chapter 15.
Joy of Life did not describe the plot of Yan Bingyun stabbing Fan Xian. This plot was adapted from the TV series Joy of Life. Therefore, it was impossible to determine which chapter of the novel Yan Bingyun stabbed Fan Xian in.
In Joy of Life, Yan Bingyun assassinated Fan Xian in chapter 15.
In Joy of Life, Yan Bingyun assassinated Fan Xian in chapter 15.
In Joy of Life, the plot where Yan Bingyun stabbed Fan Xian happened in chapter 15.
The plot of Yan Bingyun's assassination of Fan Xian in Qing Yuannian's novel happened in chapter 15.
There were many explanations for why Yan Bingyun had stabbed Fan Xian. According to the explanations in documents 1, 2, and 3, Yan Bingyun might have stabbed Fan Xian to protect the stability and interests of the Qing Kingdom. Fan Xian had discovered the collusion between the Second Prince and Eldest Princess and their illegal actions. Yan Bingyun might have thought that Fan Xian's actions would be detrimental to the Qing Kingdom, so he chose to stab Fan Xian to protect the safety of the Qing Kingdom. In addition, document 4 mentioned that in the drama version of " Celebrating Years," Yan Bingyun stabbing Fan Xian was a plan the two of them had discussed in advance. The goal was to let Yan Bingyun win the trust of the Second Prince so that he could better be a spy. Therefore, according to the information provided, the specific reason Yan Bingyun had stabbed Fan Xian might have been for the interests and stability of the Qing Kingdom, or to carry out the plan they had agreed on in advance.
Joy of Life's original novel did not describe the plot of Yan Bingyun stabbing Fan Xian, so it was impossible to determine which chapter of the original novel this plot happened in.
The original novel did not describe the plot of Yan Bingyun stabbing Fan Xian, so it was impossible to determine which chapter of the original novel this plot happened in.
Joy of Life's original novel did not describe the plot of Yan Bingyun stabbing Fan Xian. This plot was adapted from the TV series Joy of Life. Therefore, it was impossible to determine which chapter of the original work Yan Bingyun stabbed Fan Xian in.