* 8. A man may not marry his daughter-in-law.
∴ A woman may not marry her son-in-law.
** 9. A man may not marry his brother’s wife.
∴ A woman may not marry her sister's husband.
Other forbidden marriages are given in verse 17, and from the whole list many others are forbidden. Such as with one’s own sister or daughter, etc.
But in No. 9, which is the last I have mentioned, is surely the marriage forbidden by God, which men desire to make lawful—a thing which a million of Acts of Parliament cannot make lawful, because God says "it is not lawful: I am the Lord."
But it may be said, Why put sister for brother in this particular instance? Well, if we leave brother, it is absurd, for then it would be a woman may not marry her brother’s husband, which is, of course, impossible. Also is it so, if we leave wife.
It simply must be for the woman, that she cannot marry her sister’s husband. But, it is idle to talk of it being allowable for a man to marry his deceased wife's sister, when that sister is strictly forbidden by the law of God to marry him.
God, then, distinctly states that a woman