《礼记·曲礼下》
对于有道德而未曾出来作官的人，如果是年老自然死亡，就比照大夫称为 卒 ，如果是短命夭折的，就比照士称为 不禄 。
寿考曰卒，短折曰不禄。天子视不上于袷，不下于带；国君，绥视；大夫，衡视；士视五步。
For those who are virtuous but have never been officials, if they die of old age, they are called "卒" as prefects. If they die young, they are called "不禄" as scholars.