Genesis 9:12-16

As a sign of this everlasting covenant which I am making with you and with all living beings, I am putting my bow in the clouds. It will be the sign of my covenant with the world. Whenever I cover the sky with clouds and the rainbow appears, I will remember my promise to you and to all the animals that a flood will never again destroy all living beings. When the rainbow appears in the clouds, I will see it and remember the everlasting covenant between me and all living beings on earth.