“This was to fulfill
What had been spoken
By the prophet.
‘I will open my mouth
To speak in parables.
I will proclaim
What has been hidden
From the foundation
Of the world.’”
ὅπως πληρωθῇ τὸ ῥηθὲν διὰ τοῦ προφήτου λέγοντος Ἀνοίξω ἐν παραβολαῖς τὸ στόμα μου, ἐρεύξομαι κεκρυμμένα ἀπὸ καταβολῆς.
Matthew uniquely cited this prophecy from the Psalms, Psalm 78:2, where the psalmist Asaph explained the teachings from long ago. Jesus was going to open his mouth in parables about the old-fashioned sayings, like the wisdom writers. These sayings had been passed on from his ancestors, showing the great deeds of Yahweh that he had done for Israel. Jesus, via Matthew, justified or fulfilled (ὅπως πληρωθῇ) what the prophet Asaph in the psalms had said (τὸ ῥηθὲν διὰ τοῦ προφήτου λέγοντος) about the use of parables. He would open his mouth in parables (Ἀνοίξω ἐν παραβολαῖς τὸ στόμα μου) to proclaim the hidden mysteries from the foundations of the earth (ἐρεύξομαι κεκρυμμένα ἀπὸ καταβολῆς). The parables were a way of conveying wisdom, with only the initiated able to understand them.
Eugene Finnegan Bible Project 