Leviticus 20:19

And thou shalt not uncover the nakedness of thy mother’s sister, nor of thy father’s sister: for he uncovereth his near kin: they shall bear their iniquity.

Cross-reference

Leviticus 18:6 gives the overarching command against incest, which this verse applies to a specific relative.

Leviticus 18:12 also prohibits uncovering the nakedness of a father's sister, reinforcing the same kinship rule.

Leviticus 18:13-30 lists the same prohibition against a mother's sister along with many other forbidden unions, providing the fuller legal context.

Exodus 6:20 records Moses' parents marrying despite the aunt-nephew relationship later prohibited here.