What kind of arrangement is a covenant in Scripture?
In Scripture, a covenant is a one-way arrangement. It begins and ends with God alone, and men cannot touch it, enlarge it, or subtract from it. Even when confirmed, no man can annul it or add to it. It is not a humanly negotiated contract.
Les explains that Paul is speaking after the manner of men, using a human analogy. Though a man's covenant, once confirmed, cannot be annulled or added to, the Apostle is showing that from the human standpoint the Law was weak and beggarly and could not get the job done; it only pointed the finger of condemnation at mankind. But because it is a covenant, it is always a one-way street: every covenant in Scripture begins and ends with God, and men cannot touch it, enlarge it, or subtract from it. This is exactly what Paul was saying.
Brethren, I speak after the manner of men; Though it be but a man’s covenant, yet if it be confirmed, no man disannulleth, or addeth thereto.