Isaiah 6.9-10
Septuagint

kai eipe, poreuqhti, kai eipon tw law toutw, 
akoh akousete, kai ou mh sunhte, kai bleponteV bleyete, kai ou mh idhte.  epacunqh gar h kardia tou laou toutou, kai toiV wsin autwn barewV hkousan, kai touV ofqalmouV 

ekammusan:  mhpote idwsi toiV ofqalmoiV, kai toiV wsin akouswsi, kai th kardia sunwsi, kai epistreywsi, kai iasomai autouV

 

New Testament - Matthew 13.14-15

kai anaplhrountai autoiV h  profhteia Hsaiou h legousa: 
akoh akousete, kai ou mh sunhte, kai bleponteV bleyete kai ou mh  idhte.  epacunqh gar h kardia tou laou toutou, kai toiV wsin autwn barewV hkousan, kai touV ofqalmouV 
autwn 
ekammusan,  mhpote  idwsin toiV ofqalmoiV kai toiV wsin akouswsin kai th kardia sunwsin kai epistreywsin kai iasomai autouV

Mark 4.12

ina 
bleponteV blepwsin kai mh idwsin, kai akouonteV akouwsin kai mh suniwsin
mhpote 
epistreywsin kai afeqh autioV

Septuagint

And he said, Go, and say to this people, Ye shall hear indeed, but ye shall not understand; and ye shall see indeed, but ye shall not perceive.  For the heart of this people has become gross, and their ears are dull of hearing, and their eyes have they closed; lest they should see with their eyes, and hear with their ears, and understand with their heart, and be converted, and I should heal them

New Testament

Matthew 13.14-15:  And unto them is fulfilled the prophecy of Isaiah, which saith, By hearing ye shall hear, and shall in no wise understand; And seeing ye shall see, and shall in no wise perceive:  For this people’s heart is waxed gross, And their ears are dull of hearing, And their eyes they have closed; Lest haply they should perceive with their eyes, And hear with their ears, And understand with their heart, And should turn again, And I should heal them.

Mark 4.12:  that seeing they may see, and not perceive; and hearing they may hear, and not understand; lest haply they should turn again, and it should be forgiven them

Masoretic Text

And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not.  Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and turn again, and be healed

Comments:  The difference between the Septuagint and the New Testament on one hand and the Hebrew on the other is clear in the case of Matthew’s quotation.

The UBS 4th edition Greek New Testament lists Mark 4.12 as a quotation from the Septuagint, but it is not at all clear how this passage differs materially from the Hebrew.  The NRSV gives Isaiah 6.10 as:  “Make the mind of this people dull, and stop their ears, and shut their eyes, so that they may not look with their eyes, and listen with their ears, and comprehend with their minds, and turn and be healed.”

Codex Alexandrinus' reading of Isaiah 6.9-10 replaces ofqalmouV with ofqalmouV autwn, in agreement with Matthew.