Surprising restrictions[1]
לא-תתעב אדמי כי אחיך הוא לא-תתעב מצרי כי-גר היית בארצו: בנים אשר-וילדו להם דור שלישי יבא להם בקהל יקוק
Do not abhor the Edomite, for he is your brother. Do not abhor the Egyptian, for you were a sojourner in his land. Children that are born to them, [only] the third generation will enter into the congregation of Hashem[2]
The prohibition to marry an Edomite and an Egyptian convert is unique. Usually, someone of improper lineage which the Torah precludes from marriage cannot remove that blemish. They are forever forbidden, like a Moabite and an Ammonite[3]. This is not so for an Edomite and Egyptian convert. While they themselves cannot marry a regular Jew, nor their children, their grandchildren are permitted.