Albert Barnes 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)

Your brother’s wife - That is, if she had children. See (Deuteronomy 25:5). The law here expressed was broken by Antipas in his connection with Herodias (Matthew 14:3–4).