The Shoot and the Nazarene
Old Testament: Isaias 11:1
And there shall come forth a rod out of the root of Jesse, and a flower shall rise up out of his root.
New Testament: Matthew 2:23
And coming he dwelt in a city called Nazareth: that it might be fulfilled which was said by prophets: That he shall be called a Nazarene.
The connection
Matthew ends the flight into Egypt with a citation that cannot be found. The evangelist says the settling at Nazareth fulfils what was said by the prophets, then quotes a line that appears nowhere in the Old Testament in that form. Matthew also writes prophets in the plural and names none, which he does with no other quotation, so the difficulty is his own and deliberate. The traditional answer is that the fulfilment lies in the word rather than in a sentence. The shoot of Isaias 11:1 is netzer in Hebrew, and Jerome, who worked from the Hebrew rather than the Greek, states plainly that the verse reads there that a Nazarene shall grow from his root. On that reading Matthew is not quoting a lost oracle but pointing at a name: the town gives the child a title that carries the prophecy inside it, so that every time He is called the Nazarene the shoot from Jesse's stump is being said aloud by people who mean only where He lived. Nazareth was small enough that Nathanael asked whether any good thing could come out of it, which makes the hiding place of the title fitting rather than incidental.
Moral sense
The prophecy was carried in an ordinary place name and an accent, not in anything anyone would have thought to guard. What God means to preserve He does not always put somewhere impressive.
Anagogical sense
The title fixed above Him at the execution, Jesus of Nazareth, is the same word as the shoot, so the charge nailed to the Cross named the prophecy while pretending to name a village.
The Fathers
St Jerome, Letter 57, To Pammachius on the Best Method of Translating, sect. 7: "in the place where we read and translate, There shall come forth a rod out of the stem of Jesse, and a branch shall grow out of his roots, in the Hebrew idiom it is written thus, There shall come forth a rod out of the root of Jesse and a Nazarene shall grow from his root."
Warrant
Matthew 2:23 quotes no locatable Old Testament sentence and names no single prophet, so the connection cannot rest on the citation as it stands. It rests on the Hebrew word instead: Jerome, translating from the Hebrew, reports Isaias 11:1 as saying that a Nazarene shall grow from the root, and that is the reading this entry follows.
Catechism of the Catholic Church, paragraph 712.