The star out of Jacob
Whom Balaam's oracle names — David, a later king, or the Messiah — and how the star was read.
Numbers 24:15-19
15He took up his parable, and said, “Balaam the son of Beor says, the man whose eyes are open says;
16he says, who hears the words of God, knows the knowledge of the Most High, and who sees the vision of the Almighty, Falling down, and having his eyes open:
17I see him, but not now. I see him, but not near. A star will come out of Jacob. A scepter will rise out of Israel, and shall strike through the corners of Moab, and crush all the sons of Sheth.
18Edom shall be a possession. Seir, his enemies, also shall be a possession, while Israel does valiantly.
19Out of Jacob shall one have dominion, and shall destroy the remnant from the city.”
What each tradition says
Rabbinic / Midrashic
The Jewish Encyclopedia says the name Bar Kokba is only an epithet derived from R. Akiba's application of Num. xxiv. 17 to Koziba. R. Akiba applied the verse "There shall come a star out of Jacob" to Koziba, and the name Bar Kokba comes from this.
The Jewish Encyclopedia (Executive Committee of the Editorial Board), The Jewish Encyclopedia (1905), art. "Bar Kokba and Bar Kokba War" — Article, on R. Akiba's application of Num. xxiv. 17 to Bar Kokba
Patristic
Justin Martyr cites Isaiah as foretelling the same things: a star shall rise out of Jacob and a flower spring from the root of Jesse, and the nations shall trust His arm. Justin identifies this risen star of light and flower from Jesse’s root as Christ.
Justin Martyr, First Apology (ANF01. The Apostolic Fathers with Justin Martyr and Irenaeus) — Ch. 32 (on the star out of Jacob, Num. xxiv. 17)
Catholic
Haydock notes that some modern Rabbins pretend he speaks of David, who was a figure of Christ and defeated the Moabites. But he says the prophecy was perfectly fulfilled only in our Saviour, called the bright and morning star, to whom all nations were given for an inheritance.
George Leo Haydock, George Haydock's Catholic Bible Commentary — Commentary on Numbers 24:17
Orthodox
Ephraim the Syrian reads Balaam’s prophecy as fulfilled: from Jacob shone the Star, and from Israel rose the Head. He says Balaam’s prophecy had its interpreting “to-day.”
Ephraim the Syrian, Nineteen Hymns on the Nativity of Christ in the Flesh (NPNF-213. Gregory the Great (II), Ephraim Syrus, Aphrahat; J. B. Morris trans.) — Hymn I (on the prophecy of Balaam)
Reformed / Protestant
Calvin states that the coming forth of the Star and the Sceptre, which Balaam explicitly mentions, refers to Christ. He adds that what we read in the Psalm corresponds with this prophecy.
John Calvin, Harmony of the Law - Volume 4 (Charles William Bingham trans.) — On Numbers 24:17
Evangelical
Wesley says the star and sceptre here mean a great and eminent prince to come from Israel's loins, the Messiah, as both Jewish and Christian interpreters expound it. This Messiah most eminently and fully performed what is said, destroying the enemies of Israel or of God's church, described under the names of Israel's nearest and fiercest enemies.
John Wesley, Explanatory Notes upon the Old Testament — Note on Numbers 24:17