Psalm 41.9
Septuagint

kai gar o anqrwpoV thV eirhnhV mou ef on hplisa, o esqiwn artouV mou emegalunen ep eme pternismon

New Testament - John 13.18

o trwgwn mou ton arton ephren ep eme thn prernan autou
 

Septuagint

For even the man of my peace, in whom I trusted, who ate my bread, lifted up his heel against me

New Testament

He that eateth my bread lifted up his heel against me

Masoretic Text

Yea, mine own familiar friend, in whom I trusted, Who did eat of my bread, Hath lifted up his heel against me

Comments:  The NT, LXX and the MT agree.  The NT does not appear to rely upon the LXX wording in this instance.