“ ‘You shall not uncover the nakedness of your father’s wife’s daughter, conceived by your father, since she is your sister.
Not to have sexual relations with one's father's wife's daughter (half-sister through father's wife)
The cited verse
The Hebrew (Masoretic Text)
עֶרְוַת בַּת־אֵשֶׁת אָבִיךָ מוֹלֶדֶת אָבִיךָ אֲחוֹתְךָ הִוא לֹא תְגַלֶּה עֶרְוָתָהּ
In Maimonides’ words
How Maimonides defines this commandment in his Sefer HaMitzvot — his own words, shown as a primary source.
הזהיר מגלות ערות בת אשת אב כשתהיה אחותו. והוא אמרו ערות בת אשת אביך מולדת אביך אחותך היא לא תגלה ערותה, וזה הלאו בא לשים בת אשת אב ערוה בפני עצמה להיות הבא על אחותו מאביו מנשואת אביו חייב שתים משום אחותו ומשום בת אשת אביו כמו שבארנו. וזה לשונם בזה אמרו בשני מיבמות (דף כ"ב:) תנו רבנן הבא על אחותו והיא בת אשת אביו חייב שתים משום אחותו ומשום בת אשת אביו רבי יוסי ברבי יהודה אומר אינו חייב אלא משום אחותו בלבד. מאי טעמא דרבנן מכדי כתיב ערות אחותך בת אביך ערות בת אשת אביך מולדת אביך למה לי שמע מינה לחייבו משום אחותו ומשום בת אשת אביו. והעובר על זאת גם כן רוצה לומר האחות מהאב ומאם בכרת לבד אם היה מזיד, ובשוגג חייב חטאת קבועה:
He prohibited sexual intercourse with the daughter of his father's wife, when she is is sister. And that is His saying, "The nakedness of the daughter of your father's wife who is born to your father; she is your sister, you shall not uncover her nakedness" (Leviticus 18:11). And this negative commandment comes to place the daughter of the father's wife as a separate negative commandment, such that one who has sexual intercourse with his sister from his father - from his father's spouse - is liable for two: On account of [her being] his sister; and on account of [her being] the daughter of his father's wife - as we explained. And this is their language about this: They said in the second chapter of Yevamot (Yevamot 22b), "The Sages taught, 'He who has sexual intercourse with his sister, who is the daughter of his father’s wife, is liable on account of two [sins]: On account of [her being] his sister; and on account of [her being] the daughter of his father’s wife.' Rabbi Yose ben Yehuda says, 'He is liable only on account of [her being] his sister alone.' What is the reason of the Rabbis? Since it is written (Leviticus 18:9), 'The nakedness of your sister, your father's daughter,' why do I need, 'The nakedness of the daughter of your father's wife who is born to your father?' Understand from this, [that it is] to make him liable on account of [her being] his sister and on account of [her being] the daughter of his father’s wife." And one who transgresses this negative commandment as well - meaning, the sister from the father and the mother - is [punished] with excision, only when it was volitional; But if it was inadvertent, he is liable for a fixed sin-offering.
Hebrew: Sefer HaMitzvot, Warsaw 1883 (public domain). English: Sefaria Edition, trans. Rabbi Francis Nataf, 2021 (CC0). Via Sefaria; translator’s footnotes omitted.
Literary form: a prohibition
Applicability
How the catalog describes where and when this commandment applies. These are independent descriptions, not a verdict on which laws still count.
- Recorded as practiced today
Classical halakhic consequences
The consequences the classical halakhah attaches to this commandment, grouped by who imposes them. Where a category has none recorded, that absence is itself meaningful.
Imposed by a court
- Lashes (malkot)
At the hands of Heaven
- Karet — being 'cut off'
Ritual remedy
- A sin-offering (ḥatat)
How the streams of Judaism treat this commandment
The streams of Judaism read the same commandment differently — an ongoing plurality, not a ranking. Each position below is reported as the catalog records it; none is presented as the correct one.
- Orthodox Binding
- Conservative Binding
- Reform Kept as an ethical principle
- Reconstructionist Kept as an ethical principle
- Karaite Binding
24 of 613 commandments have been examined in depth so far — this one is queued.
How later traditions received this commandment
How later traditions read or reworked this commandment, each attributed to its own voice. The catalog’s own classification of each reception is shown as it records it, never adopted as GEBible’s.
Qumran (the Dead Sea Scrolls)
- 11QTa (11Q19) 66:11-17 The catalog describes this reception as: affirmed and extended
Philo of Alexandria
- De Specialibus Legibus 3.20-25 rationalized it
Josephus
- Ant. 3.274 affirmed it
The New Testament
- 1 Cor 5:1 affirmed it
The Qur'an and hadith
- Q 4:23 carried a parallel
Beside the older legal codes of its world
The commandment set beside the ancient Near-Eastern legal collections scholars compare it to — a descriptive comparison, not a claim of dependence.
- hittite laws ḫurkel (unpermitted sexual pairings); §189 addresses a man with his mother, daughter, or son, part of the §§187–200a incest/bestiality cluster — a general incest-prohibition parallel rather than a half-sister-specific one Relationship to the parallel: shared theme §189 Roth, Law Collections 2nd ed. (1997)
Where this commandment meets modern human-rights frameworks
One modern normative lens, attributed to it — not GEBible’s assessment. Each row names the framework it measures against and the catalog’s own classification of the relation.
This framework catalogues tensions; it records agreement in only one of its entries. The near-total tension rate is the shape of the instrument, not a finding.
No tension with the catalogued modern frameworks is recorded here.