'Contract' in the Bible

Now the mediator or go-between [in a transaction] is not [needed] for just one party; whereas God is only one [and was the only One giving the promise to Abraham, but the Law was a contract between two, God and Israel; its validity depended on both].

You believe that God is one; you do well [to believe that]. The demons also believe [that], and shudder and bristle [in awe-filled terror—they have seen His wrath]!