'Sign of the Covenant' in the Bible

And God said, This is the sign of the covenant that I set between me and you and every living soul that is with you, for everlasting generations:

I set my bow in the clouds, and it shall be for a sign of the covenant between me and the earth.

And God said to Noah, This is the sign of the covenant which I have established between me and all flesh that is upon the earth.

And ye shall circumcise the flesh of your foreskin; and that shall be a sign of the covenant between me and you.