Genesis 7:2

"Of every clean beast thou shalt take to thee by sevens, the male and his female: and of beasts that are not clean by two, the male and his female."

Cross References (ranked by relevance)

And Noah builded an altar unto the LORD; and took of every clean beast, and of every clean fowl, and offered burnt offerings on the altar.

And that ye may put difference between holy and unholy, and between unclean and clean;

Of clean beasts, and of beasts that are not clean, and of fowls, and of every thing that creepeth upon the earth,

And they shall teach my people the difference between the holy and profane, and cause them to discern between the unclean and the clean.