a perpetual covenant
Genesis 9:13
I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth.
Genesis 17:11
And ye shall circumcise the flesh of your foreskin; and it shall be a token of the covenant betwixt me and you.
Jeremiah 50:5
They shall ask the way to Zion with their faces thitherward, saying, Come, and let us join ourselves to the LORD in a perpetual covenant that shall not be forgotten.