DEUT1218 We must not fail to show kindness to others. Rabbi. Shimon said in the name of Rabbi Eliezer that from here we see the punishment of those who withhold kindness. During the forty years that the Israelites spent in the desert they had manna from heaven, quails, and water from the well that went with them. In addition protective clouds encircled them and journeyed before them to show them the way. In short, they lacked nothing. Nevertheless, courtesy requires that if people come from the journey, they should be welcomed with food and drink. For failure to afford the Israelites this basic courtesy, the Ammonites and Moabites were banned from entering the assembly of the Lord. This involves the exclusion of the males of these two nations from marrying a Jewess even if they converted to Judaism (Yevomos 76b). From here we see the retribution of those who failed to show kindness to those who did not need it. How much greater will the punishment be for those who do not show kindness to someone who does require it. (Vayikra Rabbah 34:8)