出处：按学科分类—语言、文字 中国对外翻译出版公司《汉英成语词典》第147页（248字）
比喻在急难中给予最需要的援助，例无须在人飞黄腾达之时锦上添花，而应该在其遭遇危难之时雪中送炭，给予援助。
Help is not needed when a person is going strong，but timely help is needed when alll is not going well and one is in the soup，as the saying goes．