1 Corinthians 7:2

Nevertheless, to avoid fornication
Or "fornications"; meaning either the frequent commission of that sin; or all sorts of uncleanness and pollution, which may be avoided by wedlock, and the proper use of the marriage bed, where the gift of continency is not bestowed: wherefore to prevent unlawful copulations, as of single persons with one another, or of a married person with a single one, the apostle advises, as being what is right and proper,

let every man have his own wife, and let every woman have her own
husband;
that is, let every man that has a wife enjoy her, and make use of her, and let every woman that has an husband, receive him into her embraces; for these words are not to be understood of unmarried persons entering into a marriage state, for the words suppose them in such a state, but of the proper use of the marriage bed; and teach us that marriage, and the use of it, are proper remedies against fornication; and that carnal copulation of a man with a woman ought only to be of husband and wife, or of persons in a married state; and that all other copulations are sinful; and that polygamy is unlawful; and that one man is to have but one wife, and to keep to her; and that one woman is to have but one husband, and to keep to him.