A man in white clothes asked an elder from Tianzhu: "Why are there hanging wooden fish in all the monks' houses?" The answer was: "To warn the public." The white clothes said: "Why must the fish be carved?" The elder could not answer, so he asked Master Bian, who said: "The fish have not closed their eyes day and night, and they also want practitioners to forget to sleep day and night, so as to achieve enlightenment."