朱子在《論語．公冶長》「我不欲人之加諸我也」章的注文中，明確提出了「仁恕之別」這一說法，依據朱子之意，「己所不欲，無施於人」與「己所不欲，勿施於人」，正可以用來表徵「仁」與「恕」的區別。這對術語僅一字之差（「無」與「勿」），然而，一為「自然而然」、自然流露而出；一為勉力而為、推而出之。朱子不僅論述了二者的區別，也闡述了二者的關聯性：做到後者（「己所不欲，勿施於人」）或處於「恕」的地位，亦須有「主敬窮理」的工夫、「漸漸勉力做向前去」，最終便可達至前者的地位（「己所不欲，無施於人」）或達至「仁」的田地。

In Gong Ye Chang of the Analects of Confucius, Zi Gong said, “What I do not wish men to do to me, I also wish not to do to men.” The Master said, “Ci, you have not attained to that.” of Zhu Xi’s commentary, Zhu Xi given a point of view--the Difference of “Ren” and “Shu”. The difference between the two is that “What you do not want done to yourself, do not do to others” (己所不欲，無施於人) and “What you do not want done to yourself, do not do to others” (己所不欲，勿施於人). There’s only one word difference, namely, “Wu” (無) and “Wu” (勿). Through the “reverential feeling” (主敬) and “study the Principle” (窮理), can be raised from “Shu” to “Ren”.