"Behold his soul which is lifted up is not upright in him but the just shall live by his faith" (Habakkuk 2: 4)
This verse is the most concise expression of the New Covenant in the Old Testament.
This verse is pregnant with meaning and expression in the original Hebrew.
"Shall live" can just as well be translated "become" or "is".
"The righteous are by faith."
"Righteousness is by faith."
B"y faith, we become righteous."
The New Testament confirms and affirms this truth, which we have in Christ:
"For if by one man's offence death reigned by one; much more they which receive abundance of grace and of the gift of righteousness shall reign in life by one, Jesus Christ." (Romans 5: 17)
"But of him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption" ( 1 Corinthians 1: 30)
"For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him. " (2 Corinthians 5: 21)
"20I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth
21I do not frustrate the grace of God: for if righteousness come by the law, then Christ is dead in vain." (Galatians 2: 20-21)
Here is another translation -- "We are righteous by His, by Jesus', faith".
Meditate on this, and let His faith live in you!