This question is related to this one about Matthew 2:14-15.
So he got up, took the child and his mother during the night and left for Egypt, where he stayed until the death of Herod. And so was fulfilled what the Lord had said through the prophet: "Out of Egypt I called my son."
Matthew 2:14-15 (NIV)
Which event according to Matthew fulfills what was spoken through the prophet? Was it the flight to Egypt? Peter Leithart treats it like this in his book The Four. Or is the fulfilling event the return from Egypt after Herod dies? This is how Craig Blomberg treats the text in the Commentary on the New Testament Use of the Old Testament edited by Beale and Carson.