Psalm 78.2
Septuagint

anoixw en parabolaiV to stoma mou, 
fqegxomai problhmata ap archV

New Testament - Matthew 13.35

anoicw en parabolaiV to stoma mou, 
ereuxomai kekrummena apo katabolhV kosmou

Septuagint

I will open my mouth in parables:  I will utter dark sayings which have been from the beginning

New Testament

I will open my mouth in parables; I will utter things hidden from the foundation of the world

Masoretic Text

I will open my mouth in a parable; I will utter dark sayings of old

Comments:  The NT, LXX and the MT agree in the first half of the quotation, but differ thereafter.