Do not have sexual relations with your sister

The nakedness of your sister, either your father's daughter or your mother's daughter, whether born at home or born outside, their nakedness you shall not uncover.

Hebrew

ט עֶרְוַת אֲחוֹתְךָ בַת-אָבִיךָ, אוֹ בַת-אִמֶּךָ, מוֹלֶדֶת בַּיִת, אוֹ מוֹלֶדֶת חוּץ--לֹא תְגַלֶּה, עֶרְוָתָן. {ס}

Greek

9 ἀσχημοσύνην τῆς ἀδελφῆς σου ἐκ πατρός σου ἢ ἐκ μητρός σου, ἐνδογενοῦς ἢ γεγεννημένης ἔξω, οὐκ ἀποκαλύψεις ἀσχημοσύνην αὐτῆς.

• Parashah: Acharei Mot
• Sefer HaChinuch: 192
• Mishneh Torah: Holiness — Forbidden Sexual Relations

• Leviticus 18:9

Enumeration and classification from BibleData. The Greek is the Septuagint reading of the same verse, carried by the source for comparison.