Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 358
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 358, with English translation by Maimonides (Rambam).
שלא יגרש האונס אנוסתו, שנאמר "לא יוכל שלחה, כל ימיו" (דברים כב,כט).
For a rapist not to divorce the woman he raped, as [Deuteronomy 22:29] states: "He may not send her away for his entire life."