According to McConkie and Millet, apparently Zenos is the prophet that Nephi is quoting. It appears also that Malachi either quoted Zenos or received an independent revelation in the same terms (see verses 15, 23-24; Malachi 4:1-2; 3 Nephi 24:1; 25:1; New Witness, p. 563) [Joseph Fielding McConkie and Robert L. Millet, Doctrinal Commentary on the Book of Mormon, Vol. 1, p. 175]
“The Prophet”
According to Monte Nyman, in 1 Nephi 22:15-17 we find evidence of a section of scripture found on the Plates of Brass but not in the King James Version of the Bible. In his work on Isaiah, Nyman noted a significant addition to Isaiah: "As Nephi commented on Isaiah 49 in 1 Nephi 22:15-17, he quoted or paraphrased three verses from 'the prophet,' obviously Isaiah. We do not have these verses in the present Bible text, but they fit very well into the context of Isaiah 49 and 50. We can illustrate this by placing (1 Nephi 22:15-17) between the last verse of chapter 49 and the first verse of chapter 50." [Monte Nyman, Great Are the Words of Isaiah, p. 191]