Sefer Otzar Yisroel relates in the name of Rav Mordechai Chaim of Slonim zy”a that Rav Eliezer Lipman zt”l, the father of Rav Zushe and Rav Elimelech zy”a, once came across a gentile who was dragging along the road a Jew tied to the tail of a horse. He approached the gentile and asked him to let the Jew go, and he offered to pay him whatever was owed. The gentile refused until he promised to give him all the money he had with him. Finally, the non-Jew relented and released the Jew.
The Jew asked R’ Eliezer Lipman what he could do to repay him, but he said that he didn’t want anything. The Jew then told him, “I will take on me the punishments of Gehenim that you would have otherwise received.” R’ Eliezer Lipman agreed to this.
Some years later, that Jewish man appeared at the house of R’ Eliezer Lipman and said, “I have already died and passed on to the next world. I already received my deserved punishment in Gehenim. I now am supposed to endure the Gehenim I accepted to do for you. I don’t think I can endure such terrible suffering again. I ask you to please forgo my promise to you.”
R’ Eliezer Lipman said, “Of course I will do that. I would never want someone to suffer because of me.”
At that moment, an announcement rang out from Heaven, saying, “As reward for this act, R’ Eliezer Lipman will have two sons who will take Jewish people out of Gehenim.”
