Galatians 3:15
"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."
Cross References (ranked by relevance)
Hebrews 9:17
For a testament is of force after men are dead: otherwise it is of no strength at all while the testator liveth.
Romans 6:19
I speak after the manner of men because of the infirmity of your flesh: for as ye have yielded your members servants to uncleanness and to iniquity unto iniquity; even so now yield your members servants to righteousness unto holiness.
Romans 3:5
But if our unrighteousness commend the righteousness of God, what shall we say? Is God unrighteous who taketh vengeance? (I speak as a man)