During the Han Dynasty, Pang Can, the governor of Hanyang, heard about the talents of the recluse Ren Tang and wished to invite him to serve as an advisor. Pang Can went to Ren Tang's door and explained his intentions.

Ren Tang remained silent. Instead, he placed a basket of scallions and a basin of water outside his door, then hid nearby with his grandson.

Pang Can's subordinates initially thought Ren Tang was being arrogant, but Pang Can immediately understood his meaning. The basin of clear water symbolized purity and incorruptibility, representing Ren Tang's expectation that Pang Can should govern justly and without corruption. The scallions, a common vegetable, hinted that Pang Can should care for the common people.

This act expressed the people's deep expectation for an official to be as pure and clear as water.