During the Warring States period, Lord Pingyuan of Zhao needed to seek military aid from the King of Chu. He intended to bring twenty retainers but only had nineteen. Mao Sui volunteered to fill the last spot.

When negotiations with the King of Chu reached a stalemate, Mao Sui, stepping forward with his sword, compelled the King of Chu to swear an alliance with Zhao against Qin.

Afterward, Mao Sui ridiculed the other retainers who had accompanied them, implying they were '庸庸碌碌' (yōngyōng lùlù), meaning they were ordinary and achieved nothing significant on their own, succeeding only through others' efforts. This story illustrates the contrast between Mao Sui's decisive action and the unremarkableness of others, reflecting the idea of being '碌碌无奇' – ordinary and without distinction.