Deuteronomy 6.4-5
Septuagint


akoue  Israhl, 
kurioV o qeoV hmwn, kurioV eiV esti. 
kai agaphseiV kurion ton qeon sou 

ex olhV thV dianoiaV sou, 
kai ex olhV thV yuxhV sou, 
kai ex olhV thV dunamewV sou

New Testament - Mark 12.29-30

apekriqh o  IhsouV oti prwth estin: 
akoue,  Israhl, 
kurioV o qeoV hmwn kurioV eiV estin, 
kai agaphseiV kurion ton qeon sou
ex olhV thV kardiaV sou 
kai ex olhV thV yuxhV sou 
kai ex olhV thV dianoiaV sou 
kai ex olhV thV isxuoV sou

Septuagint

Hear, O Israel, The Lord our God is one Lord.  And thou shalt love the Lord thy God with all thy mind, and with all thy soul, and with all thy strength
 

New Testament

Jesus answered, The first is, Hear, O Israel; The Lord our God, the Lord is one:  and thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind, and with all thy strength

Masoretic Text

Hear, O Israel:  Jehovah our God is one Jehovah:  and thou shalt love Jehovah thy God with all thy heart, and with all thy soul, and with all thy might

Comments:  The NT replaces the Greek word dunamewV for strength with iscuoV.

In a sense, the NT disagrees with both the MT and the LXX.  That is, the NT includes the “mind” from the LXX, absent from the MT, and includes the “heart,” absent from the LXX, but present in the MT.

The analysis shifts but reaches a similar conclusion if we consider a textual variant.  Brenton’s Septuagint is based on Codex Vaticanus.  Codex Alexandrinus gives “heart” where Vaticanus has  “mind.”  This variation brings the Septuagint into agreement with the MT; but the NT, inserting  “with all thy mind,” still differs from both the Hebrew and the Old Testament Greek.