耿耿于怀[在心] [- - yú huái]take sth. to heart; an uneasy heart; an unsettled or disturbed mind; brood on (an injury, one's neglected duty, etc.); constantly remembering in one's heart; deeply concerned at heart; stick in one's throat; take ... too much to heart：
•¶ 同志之间有些小矛盾， 过去就算了， 不要老是耿耿于怀[在心]。 Forget about trivial disagreements among comrades, and don't take them to heart.