פירוש על קידושין 34:19

A different baraita states that the sages were pleased with one who repays the converts converted children. [Note that the simple reading of these two sources is that there was some dispute over the matter. Some rabbis thought that it is always good to pay one’s debts. Other rabbis feared that by repaying the converted children, there would not be recognition that conversion is like rebirth. In other words, which is more important, money or ideology?]
The Talmud, as it usually does, harmonizes the two sources. If the child was conceived and born before the father and the children converted, then the sages did not want the borrower to repay the debt. But if the child was conceived, and then the parents converted, while the child still does not inherit from his parents, the rabbis were pleased with one who repaid the debt.