Rambam - Sefer HaMitzvos: Negative Mitzvot 52, 53, 55, 54, 354, 360, 361: Negative Mitzvot 52, 53, 55, 54, 354, 360, 361

Negative Mitzvah 52: The prohibition of intermarriage
Deuteronomy 7:3 "Neither shall you make marriages with them"

We are forbidden to marry non-Jews.

Negative Mitzvah 53: We are forbidden to marry a man from the Ammonite or Moabite nations
Deuteronomy 23:4 "An Ammonite or a Moabite shall not enter the congregation of G-d"

We are not allowed to marry a man from the nations of Ammon or Moab even if he has converted to Judaism.

However, it is permissible to marry a woman from Ammon or Moab after she has converted to Judaism.

These nations refused to offer bread and water to the Jewish people when they passed by their borders and because of this act of cruelty, they were excluded from ever being able to join the Jewish people in marriage.

Negative Mitzvah 55: We are forbidden to reject an Egyptian if he converts to Judaism
Deuteronomy 23:8 "Do not despise an Egyptian because you were a stranger in his land"

The Torah forbids an Egyptian convert from marrying freely into the Jewish people until the third generation.

The hundreds of years of cruel slavery in Egypt affected both nations. Nevertheless, despite the hardships in Egypt, the Torah appreciates that Jacob and his sons were given refuge in Egypt. Also, it was in Egypt that the Jewish people developed into a nation to be chosen by HaShem.

Therefore, we are commanded not to totally reject an Egyptian that converts to Judaism. The third generation of such converts may marry freely among the Jewish people.

Negative Mitzvah 54: We are forbidden to reject an Edomite if he converts to Judaism
Deuteronomy 23:8 "Do not despise the Edomite, since he is your brother"

The Edomite nation descends from Esau, Jacob's brother.

Esau left his descendants a heritage of murder and theft.

Therefore, different laws apply to converts from the Edomite nation than to converts from other nations.

They may not marry freely among the Jewish people until the third generation. Nevertheless, since they descended from our forefathers and they are, in essence, our brothers, we may not totally reject them.

Therefore, the third generation of Edomite converts may marry freely among the Jews. We are prohibited from refusing to intermarry with them.

Negative Mitzvah 354: A "Mamzer" may not marry freely within the Jewish community
Deuteronomy 23:3 "A Mamzer shall not enter into the assembly of the L-rd"

A "Mamzer" is a child that is born as a result of certain forbidden relationships.

This Negative Mitzvah forbids a Mamzer from marrying freely among Jews.

Negative Mitzvah 360: Restriction on a disabled man
:blue: Deuteronomy 23:2 "He that is crushed or maimed in his private parts shall not enter the assembly of the L-rd"

A male whose manhood is so physically disabled that he cannot have children is cautioned not to marry a Jewish woman.

This prohibition only applies to those disabilities that a man brings upon himself and not those caused by illness or other afflictions that are not his fault.

Negative Mitzvah 361: It is forbidden to disable males from fathering children
Leviticus 22:24 "Neither shall you do this in your land"

We are forbidden to disable a male - man or animal - from fathering children.

In truth, there are two possible channels by which to receive your livelihood, according to the perspective you take in life: You could decide to become just another element of nature, chasing after your bread in the chaos, running the race of survival of the fittest. And the fact is, you may even do well taking this route -- in the short run. In the long run, however, your soul is being denied its nourishment, and your body, too, will never feel satisfied.
Or you could see your life as an intimate relationship with the Source of Life Above -- as though all your livelihood was no more than manna from heaven, handed to you personally and lovingly straight from the hand of your G-d and partner in all you do.
Then your main job is to keep the basket where your manna will fall sparkling clean, insuring that no one is being hurt or misled by your business. To spend the profits you are granted on spreading kindness in the world. Maybe you'll get rich this way. Maybe you won't. But you will always be satisfied.

From: Bringing Heaven Down to Earth by Tzvi Freeman - tzvif@aol.com