一飯三遺矢
yī​fàn​sān​yí​shǐ

physically weak from old age

  1. 一 yī numeral
    one
    one; the number 1; single; alone
  2. 饭 飯 fàn noun
    meal
    a meal; daily food
  3. 三 sān numeral
    three
    the number three; 3
  4. 遗矢 遺矢 yí​shǐ
    to defecate
    (literary) to defecate; to relieve oneself. Often used in literary contexts to describe incontinence as a sign of old age or physical decline. In this sense 矢 shǐ is used identically to 屎 shǐ