The Greek verb emmenō means to remain in, to continue, to abide by, or to persevere in. Composed of en ('in') and menō ('to remain, abide'), it emphasizes steadfast continuation in a commitment, covenant, or course of action. It appears four times in the New Testament.
Hebrews 8:9 uses emmenō in the quotation of Jeremiah 31:32: Israel 'did not remain faithful to my covenant' — pointing directly to the failure of the old covenant and the necessity of the new. The new covenant's superiority rests precisely on the promise of internal transformation that enables what external law could not produce: genuine, lasting faithfulness.
Galatians 3:10 warns that 'everyone who does not continue (emmenō) in everything written in the Book of the Law is under a curse.' This is Paul's argument that the law itself condemns those who rely on it, since no one emmenō in perfect obedience — thus the necessity of faith in Christ who absorbed the curse (Galatians 3:13).