How beautiful upon the mountains are the feet of him that bringeth good tidings, that publisheth peace; that bringeth good tidings of good, that publisheth salvation; that saith unto Zion, Thy God reigneth! (Isa 52:7)
Abinadi’s interpretation of this verse in the book of Isaiah can be found in Mosiah 15:13-18:
Yea, and are not the prophets, every one that has opened his mouth to prophesy, that has not fallen into transgression, I mean all the holy prophets ever since the world began? I say unto you that they are his seed. And these are they who have published peace, who have brought good tidings of good, who have published salvation; and said unto Zion: Thy God reigneth! And O how beautiful upon the mountains were their feet! And again, how beautiful upon the mountains are the feet of those that are still publishing peace! And again, how beautiful upon the mountains are the feet of those who shall hereafter publish peace, yea, from this time henceforth and forever! And behold, I say unto you, this is not all. For O how beautiful upon the mountains are the feet of him that bringeth good tidings, that is the founder of peace, yea, even the Lord, who has redeemed his people; yea, him who has granted salvation unto his people;
As John Tvedtnes noted:
This interpretation is strikingly similar to the one found in one of the Dead Sea Scrolls, 11QMelchizedek (11Q13), column II, lines 15-19:
This is the day of [peace about which God] spoke [of old through the words of Isa]iah the prophet, who said: ‘How beautiful upon the mountains are the feet of the messenger who announces peace, of the mess[enger of good who announces salvation,] saying to Zion: “your God [reigns.”] Its interpretation: The mountains are the pro[phets . . . ] And the messenger is [the ano]inted of the spirit about whom Dan[iel] spoke [ . . . and the messenger of] good who announces salv[ation is the one about whom it is written that [he will send him] “to comfo[rt the afflicted, to watch over the afflicted ones of Zion."] (Florentino García Martínez, The Dead Sea Scrolls Translated [2nd ed., Leiden: Brill, 1996], 140)
The latter portion of the text is actually from Isaiah 61:2-3, and is the one that speaks about being anointed of the spirit (rather than Daniel, who wrote only about the Messiah or "anointed one" in Daniel 9:24-26). This is the passage that Jesus cited in reference to his messianic calling (Luke 4:18-19, see verses 17-21). The interpretation of the Isaiah passage in the Qumran scroll accords with Abinadi's teachings. It also supports Jesus' statement in 3 Nephi 28:39-40, in which he indicates that the prophecy in Isaiah 52:7 refers to him.
The concept of the prophets being represented by the mountains is paralleled by the rabbinic interpretation, found in several sources, of the expression "top of the hill" in Exodus 17:9, where "top" is said to refer to the patriarchs and "hill" to the matriarchs. Early Jewish Aramaic translations of the Bible reflect this idea. Thus, in Targum Neofiti and Targum Pseudo-Jonathan to Numbers 23:9 and Deuteronomy 33:15, the patriarchs (Abraham, Isaac, and Jacob) are compared to the mountains while their wives (Sarah, Rebekah, and Leah) are compared to the hills. In medieval Jewish texts such as Zohar Exodus 58b and Pesikta Rabbati 33:4 Abraham, Isaac, and Jacob are termed "the three mountains of the world." (John A. Tvedtnes, The Most Correct Book: Insights from a Book of Mormon Scholar [Bountiful, Utah: Cornerstone, 1999], 174-75)
With respect to Targum Pseudo-Jonathan, here is the interpretation of Num 23:9:
For, said Bileam the wicked, I look on this people who are led on for the sake of their righteous fathers, who are like the mountains, and of their mothers, who are like the hills: behold, this people alone are to possess the world, because they are not led by the laws of the nations. (source)
Here is the interpretation of Deut 33:15:
and with the goodness through the birthright ordained of the mountain tops, him at the beginning by the benediction of the fathers who resemble the mountains, and with the goodness of the hills whose produce faileth not, which was given him in heritage by the benedictions of the mothers of old, who resemble the hills; (source)
The support for the Book of Mormon's interpretation of Isa 52:7 from ancient texts serve as evidence for its antiquity and authenticity.