Brothers, let me put this in human terms. Even a human covenant, once it is ratified, cannot be canceled or amended.
KJV
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.
ASV
Brethren, I speak after the manner of men: Though it be but a man’s covenant, yet when it hath been confirmed, no one maketh it void, or addeth thereto.