"Additionally, this outlook helps resolve disputes and removes hatred from man's heart. And when there will be peace among people, Hashem will grant them peace... Someone who places in his heart to hate his fellow man for the bad he caused him and takes revenge has transgressed this prohibition. This is very bad; it leads to many troubles."
The Tosher Rebbe zt'l would send money to a particular person every year. His gabbai asked, "Why do you send money to him? He isn't poor!" The Rebbe of Tosh explained, "I was once in an area with only one mikvah. It was just a hole in the ground, and a wooden plank was used to cover the mikvah when it wasn't in use. Once, I was immersed in this mikvah, and this person was there, and he covered the mikvah with the plank! He intentionally wanted to harm me! My life was in danger! But then he lifted the plank, and this saved me. I don't consider him guilty for covering the mikvah. I know that he was sent from heaven to do that. But he deserves credit for removing the plank to save me. I send him money as hakaras hatov."
The Imrei Emes zt'l lived in Biyale (his wife's hometown) after his chasunah. One of the locals caused him a lot of anguish. During World War One, this man (who had bothered the Imrei Emes) needed help, and the Imrei Emes sent him food and clothing and helped him immensely.
The Imrei Emes's Rebbetzin quipped, "I see that you can't forget all the trouble he caused you." Another time, she said, "I understand that you want to repay his evil ways with kindness because there is a virtue to משלם רעה תחת טובה, to pay back good for the bad you received, however, he wasn't so cruel to you that you should help him so much."
The Imrei Emes replied with the pasuk (Mishlei 17:13), which discusses the opposite scenario: when people act cruelly to those who did kindness to them. It states רעה משב מביתו רעה תמוש לא טובה תחת, "He who repays evil for good, evil will not depart from his house." The pasuk discusses when one does bad to a person who has helped him. The pasuk warns that he will be punished severely. Evil and troubles will not depart from his house."
