Psalm 51.4
Septuagint

soi monw hmarton, kai to ponhron enwpion sou epoihsa: 

opwV an dikaiwqhV en toiV logoiV sou, 
kai nikhshV en tw krinesqai se

New Testament - Romans 3.4

mh genoito:  ginesqw de o qeoV alhqhV, paV de anqrwpoV yeusthV, kaqwV gegraptai: 
opwV an dikaiwqhV en toiV logoiV sou 
kai nikhseiV en tw kpinesqai se

Septuagint

Against thee only have I sinned, and done evil before thee:  that thou mightest be justified in thy sayings, and mightest overcome when thou art judged

New Testament

God forbid:  yea, let God be found true, but every man a liar; as it is written, That thou mightest be justified in thy words, and mightest prevail when thou comest into judgment

Masoretic Text

Against thee, thee only, have I sinned, And done that which is evil in thy sight; That thou mayest be justified when thou speakest, and be clear when thou judgest

Comments:  The agreement between the LXX and the NT is nearly exact.  The MT replaces the concept of victory in judgment with that of being “clear” or “blameless” (RSV) in judgment.