Imamat 18:11

18:11 You must not have sexual intercourse with the daughter of your father’s wife born of your father; she is your sister. You must not have intercourse with her. ¹ 

Imamat 18:20

18:20 You must not have sexual intercourse ²  with the wife of your fellow citizen to become unclean with her.

[18:11]  ¹ tn Heb “The nakedness of the daughter of your father’s wife born of your father, she is your sister; you must not uncover her nakedness.” That is, a half sister, the daughter of the man’s father by another wife, who is not the man’s mother, is to be considered a true sister. Therefore, the man must not have sexual intercourse with her.

[18:20]  ² tn Heb “And to the wife of your fellow citizen you shall not give your layer for seed.” The meaning of “your layer” (שְׁכָבְתְּךָ, shÿkhavtÿkha) is uncertain (see B. A. Levine, Leviticus [JPSTC], 122, “you shall not place your layer of semen”; but cf. also J. E. Hartley, Leviticus [WBC], 283, and the literature cited there for the rendering, “you shall not give your penis for seed”).