Charles Ellicott Commentary Leviticus 18:16

"Thou shalt not uncover the nakedness of thy brother`s wife: it is thy brother`s nakedness." — Leviticus 18:16 (ASV)

The nakedness of your brother’s wife. — Although a union with a brother’s wife is forbidden here—this prohibition, according to the administrators of the law during the Second Temple period, extended to illicit relations or marriage if she was divorced from her husband during his lifetime—and though offenders are threatened with the curse of childlessness , yet the law on this point is by no means absolute. Under certain conditions, the law commands it as a moral and civil duty for a man to marry his brother’s widow.

If a brother dies without children, it is obligatory for each surviving brother in succession to marry the widow. If the brother-in-law refused to perform this sacred duty, the widow made him undergo a ceremony in which she subjected him to the greatest humiliation. This clearly shows that the prohibition here could not be based on incest, since the Divine law itself would never, under any circumstances, have set aside something inherently incestuous. The surviving brother-in-law had to perform this duty for the widows of as many of his brothers as happened to die without children. A striking illustration of this occurred while Judah the Holy was president of the Sanhedrin. Twelve widows appealed to their brother-in-law to perform the duty of Levir.

He refused to marry them because he saw no way to support such an additional number of wives and, possibly, a large increase in children. The case came before the President of the Sanhedrin. The President not only decided that the man must marry them all but also promised that if he would perform the duty commanded by the Law of Moses, he himself would support the family, and their children if there were any, every Sabbatical year when no produce was gathered from the land, which was at rest. The Levir, accepted the offer and accordingly married his twelve sisters-in-law.

After three years, these twelve wives appeared with thirty-six children before Judah the Holy to claim the promised support, as it was the Sabbatical year, and they actually received it. This law is still in force today among Orthodox Jews. When a man dies without children, the widow ipso facto belongs to the surviving brother. She is not allowed to marry anyone else unless her brother-in-law has undergone the ceremony of publicly renouncing her, which is equivalent to a divorce. This will explain the rendering of the clause before us in the ancient Chaldee Version: “You shall not uncover the nakedness of your brother’s wife in the lifetime of your brother or after his death if he has children.”