Contrast with Unclean.
Clean Animals
Preservation of the clean animals in the ark
7 days before the flood waters came, the Lord told Noah to go into the ark with his household and 7 pairs of all clean animals.
"Go into the ark, you and all your household, for I have seen that you are righteous before me in this generation. Take with you seven pairs of all clean animals, the male and his mate, and a pair of the animals that are not clean, the male and his mate, and seven pairs of the birds of the heavens also, male and female, to keep their offspring alive on the face of all the earth. For in seven days I will send rain on the earth forty days and forty nights, and every living thing that I have made I will blot out from the face of the ground."
During the flood, all flesh died apart from those who were with Noah in the ark.
Noah's burnt offering
After leaving the ark, Noah built an altar to the Lord and took some of every clean animal and every clean bird and offered burnt offerings. When the Lord smelled the pleasing aroma, He said in His heart, "I will never again curse the ground because of man, for the intention of man's heart is evil from his youth. Neither will I ever again strike down every living creature as I have done. While the earth remains, seedtime and harvest, cold and heat, summer and winter, day and night, shall not cease.”