The 219th mitzvah is the law of a motzi shem ra [i.e., one who marries a virgin and falsely accuses her of having relations between the kidushin1 and the n'suin] — that we are commanded to give him lashes, and that he remain married to her, for he also2 is instructed,3 "He must then take her as his wife, and he may not send her away as long as he lives."

It is explained in tractate Makkos4 that this prohibition, is like that of a rapist, i.e., it is considered a "prohibition which is preceded by a positive commandment."

The details of this mitzvah are explained in the third and fourth chapters of Kesubos.