Leviticus 18:6

None of you shall approach to any that is near of kin to him, to uncover their nakedness: I am the LORD.

None of you shall approach to any that is near of kin, х 'iysh (H376) 'iysh (H376) ... lo' (H3808) tiqrªbuw (H7126)] - no man of you shall approach in conjugal connection (Leviticus 18:14; Genesis 20:4; Deuteronomy 22:14; Isaiah 8:3; Ezekiel 18:6). х lªgalowt (H1540) `erwaah (H6172), to have sexual intercourse (Genesis 4:1; Deuteronomy 22:30). These two phrases, the last of which is exegetical of the former, are synonymous: shª'eer (H7607) bªsaarow (H1320), flesh by (of) flesh - i:e., blood-relations.] This is a general law, prohibitory of all incestuous alliances, and it is expressed in terms sufficiently explicit to have superseded the necessity of entering into details. But in legislating for a people low in the scale of moral perception a minute specification of the permissive limits was needed; and hence, this summary, though comprehending in itself the following details, was expounded by an enumeration of the degrees within which every kind of sexual intercourse-particularly that of marriage-was absolutely forbidden. These injunctions are, without exception, addressed to men.

Very great laxity prevailed among the Egyptians in their sentiments and practice about the conjugal relation, as they not only openly sanctioned marriages between brothers and sisters, but even between parents and children. Such unnatural alliances Moses wisely prohibited; and his laws form the basis on which the marriage regulations of this and other Christian nations are chiefly founded.