6:18. And I will establish my covenant with thee, and thou shalt enter
into the ark, thou and thy sons, and thy wife, and the wives of thy sons
with thee.

6:19. And of every living creature of all flesh, thou shalt bring two of
a sort into the ark, that they may live with thee: of the male sex, and
the female.

6:20. Of fowls according to their kind, and of beasts in their kind, and
of every thing that creepeth on the earth according to its kind: two of
every sort shall go in with thee, that they may live.

6:21. Thou shalt take unto thee of all food that may be eaten, and thou
shalt lay it up with thee: and it shall be food for thee and them.

6:22. And Noe did all things which God commanded him.

Genesis Chapter 7

Noe with his family go into the ark. The deluge overflows the earth.

7:1. And the Lord said to him: Go in, thou and all thy house, into the
ark: for thee I have seen just before me in this generation.

7:2. Of all clean beasts take seven and seven, the male and the female.

Of all clean... The distintion of clean and unclean beasts appears to
have been made before the law of Moses, which was not promulgated till
the year of the world 2514.