The ninth behest is this: ‘Thou shalt not desire thy neighbour’s wife,
nor desire her in thy heart.’ That is to say, thou shalt not consent to
do sin with thy body.
This behest forbids to desire with will of heart to have carnal
fellowship with all women out of marriage; and the sinful tokens that
are made outwardly in order to lead to sin, as are sinful words of such
a kind, or gifts, or sinful handling. And the difference between this
behest and the sixth aforesaid is, that the sixth behest forbids the
deed without, but this forbids the consent within. For the consent to
have carnal fellowship with a woman (women), who is not his own for a
wife, is deadly sin by the judgment of God’s Word, which says: ‘Whoever
sees a woman and desires her in his heart, he hath sinned with her in
his heart,’ that is to say, in open desire and in thought.