In the biblical Book of Genesis, God gives Noah a rainbow as the sign of the covenant after the Flood.
Genesis 9:12–17 describes the rainbow as the sign of God’s covenant with Noah, his descendants, and every living creature. God says that whenever the rainbow appears in the clouds, the covenant will be remembered: the waters will not again become a flood to destroy all life.
The covenant is broader than Noah’s immediate family. It includes animals and the earth itself, making it a universal post-Flood promise within the biblical narrative. Genesis places the sign in the clouds, linking a visible natural phenomenon with the story’s theological meaning.
An olive branch is connected with the dove’s return in Genesis 8, but it is not the covenant sign named in Genesis 9. Likewise, a burning bush and pillar of fire belong to other biblical episodes. The canonical answer here is the rainbow.