[rěn xīn]
have the heart to; be hardhearted enough to; pitiless; hardhearted
cannot bear to; cannot stand the sight of
不忍心
He didn't have the heart to [couldn't bear to] turn down their request.
他不忍心拒绝他们的要求。
As doctors, how can we have the heart to watch patients suffer pain and do nothing?
我们作大夫的难道忍心看着病人受痛苦吗?