Rambam - Sefer HaMitzvos: Negative Mitzvah 355: Negative Mitzvah 355

This is not an error of duplication. The full-fledged version of this Mitzvah are many and change for those who are learning the one/three chapter a day. The Message for the day from "Bringing Heaven Down to Earth" at the end of this Mitzvah is different than that of yesterday.

Negative Mitzvah 355: It is forbidden to take a woman as a wife without marriage
Deuteronomy 23:18 "There shall be no indecent women among the daughters of Israel"

A Jewish marriage must be held according to the law of the Torah.

This includes the entire wedding ceremony with all its details and procedures and the signing of the marriage contract.

A person is forbidden to take a woman as a wife without fulfilling these requirements.

Every word of Torah is a story in your life, at every point of living. First, Noah was told to enter the ark. Later he was told to leave the ark and enter a new world.
You must do both. First enter your ark, then leave to enter the world. If your ark was a real ark, then the world you will enter will not be the same world you just left.

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