This Bible contradiction is from the Skeptic's Annotated Bible.

Verses

He shall be unclean for seven days.

Leviticus 15:24 View context

And if any man lie with her at all, and her flowers be upon him, he shall be unclean seven days; and all the bed whereon he lieth shall be unclean.

He and the woman shall be cut off from among their people.

Leviticus 20:18 View context

And if a man shall lie with a woman having her sickness, and shall uncover her nakedness; he hath discovered her fountain, and she hath uncovered the fountain of her blood: and both of them shall be cut off from among their people.