... Now the Sixth Commandment enters in, because it forbids adultery, which is the breaking of the marriage vow between the husband and wife. How is it that the Tenth Commandment also refers to the wife? Luther showed this in the Large Catechism by reference to a ‘rich bride.’ A wife is valuable to her husband in two ways. First of all she is someone to love and be loved. She is also a helper in many ways. She does housework such as cleaning, sewing and cooking. She might do this for other people also without breaking her marriage vow. But some women are so busy working for other people that they aren’t able to help in their own family as they should. When this happens it is because someone is breaking the Tenth Commandment. It is not always easy to show who is at fault in such a case. That is why people have trouble distinguishing these two commandments.
Nils C. Oesleby, "The Distinction between the Sixth, Seventh, Ninth, Tenth Commandments," Lutheran Sentinel, 9 May 1963, 138-40, at 139.
