A story with Shema'yah and Avtalyon: Yoma 71b
A Court Bending the law in a Convert's Case is guilty of "Bending Hashem's judgment": Chagigah 5a Prohibition against abusing a descendant of converts by reminding him of his parents' pre-conversion deeds: Bava Metzia 58b
Special prohibitions against abusing a person who has converted to Judaism: Bava Metzia 59b