Charles Ellicott Commentary Leviticus 18:17

"Thou shalt not uncover the nakedness of a woman and her daughter; thou shalt not take her son`s daughter, or her daughter`s daughter, to uncover her nakedness; they are near kinswomen: it is wickedness." — Leviticus 18:17 (ASV)

A woman and her daughter. —This means that if a man marries a widow who has a daughter from a former husband, or if he forms a union with a woman who has a daughter born out of wedlock, he is also forbidden to marry the daughter.

However, although this prohibition is directed against a particular form of polygamy, there can hardly be any doubt that, according to the interpretation of the law's administrators during the Second Temple period, if he married either of them and she died, he could no longer marry the other. Furthermore, this prohibition did not apply to cases of illicit sexual relations. Criminal sexual relations with one did not prevent him from marrying the other. For engaging in the kind of polygamy forbidden here, the offenders were punished with death by fire .