麻木不仁

má mù bù rén

numb and unfeeling; apathetic

Character by character

麻má
numb

木mù
numb

不bù
not

仁rén
feeling

看到别人有困难却麻木不仁，这样的人太可怕了。

To see others in difficulty and feel nothing: such people are frightening.

Tone: negative (criticism).

In medicine 不仁 meant a limb with no sensation.

Learn this in Lesson 210 · HSK 9+: 鲁迅与白话文 (Lu Xun and the birth of modern writing)

A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.