Wu Dashan and Wu Xiaoshan assaulted An Fu simply because they were too jealous.
You see, lately the An family had been delivering tofu to Jiuping Village, even though the village had its own tofu vendor. An Jing and Xiao Changyi, however, went out of their way to bypass the local vendor and instead purchased a lot of tofu from the An family!
Every time the An family brought tofu into Jiuping Village, their family would be mocked, with people saying the Ans were on their way to riches while their own tofu just wouldn't sell.
Rather than say the brothers envied and resented An Fu, it was more accurate to say they resented An Jing and Xiao Changyi. If only Changyi and An Jing had bought tofu from them instead of the An family, none of this would've happened: they wouldn't be a laughingstock, and they could have sold a lot of tofu and made a good sum!
