Genesis 6:12-14, 19-20, 22

God looked on the earth, and behold, it was corrupt; for all flesh had corrupted their way upon the earth. Then God said to Noah, “The end of all flesh has come before Me; for the earth is filled with violence because of them; and behold, I am about to destroy them with the earth. Make for yourself an ark of gopher wood; you shall make the ark with rooms, and shall cover it inside and out with pitch.

And of every living thing of all flesh, you shall bring two of every kind into the ark, to keep them alive with you; they shall be male and female. Of the birds after their kind, and of the animals after their kind, of every creeping thing of the ground after its kind, two of every kind will come to you to keep them alive.

Thus Noah did; according to all that God had commanded him, so he did.