Maimonides, a letter to Yemen, 12th century
What is to be the manner of Messiah's advent, and where will be the place of his appearance? . . . And Isaiah speaks similarly of the time when he will appear, without his father or mother of family being known, He came up as a sucker before him, and as a root out of the dry earth, etc. But the unique phenomenon attending his manifestation is, that all the kings of the earth will be thrown into terror at the fame of him -- their kingdoms will be in consternation, and they themselves will be devising whether to oppose him with arms, or to adopt some different course, confessing, in fact, their inability to contend with him or ignore his presence, and so confounded at the wonders which they will see him work, that they will lay their hands upon their mouth; in the words of Isaiah, when describing the manner in which the kings will hearken to him, At him kings will shut their mouth; for that which had not been told them have they seen, and that which they had not heard they have perceived.
The Babylonian Talmud
The Messiah -- what is his name?...The Rabbis say, the leprous one; those of the house of Rabbi say, the sick one, as it is said, "Surely he hath borne our sicknesses." (Sanhedrin 98b)
Rabbi Moshe Kohen ibn Crispin, Spanish 15th-century rabbi
"This passage, the commentators explain, speaks of the captivity of Israel, although the singular number is used in it throughout. Others have supposed it to mean the just in this present world, who are crushed and oppressed now... but these too, for the same reason, by altering the number, distort the verses from their natural meaning. And then it seemed to me that...having forsaken the knowledge of our Teachers, and inclined "after the stubbornness of their own hearts," and of their own opinion, I am pleased to interpret it, in accordance with the teaching of our Rabbis, of the King Messiah."
Nachmanides (R. Moshe ben Nachman)(13th c.)
The right view respecting this Parashah is to suppose that by the phrase "my servant" the whole of Israel is meant. . . .As a different opinion, however, is adopted by the Midrash, which refers it to the Messiah, it is necessary for us to explain it in conformity with the view there maintained. The prophet says, The Messiah, the son of David of whom the text speaks, will never be conquered or perish by the hands of his enemies. And, in fact the text teaches this clearly. . . .
And by his stripes we were healed -- because the stripes by which he is vexed and distressed will heal us; God will pardon us for his righteousness, and we shall be healed both from our own transgressions and from the iniquities of our fathers.
Driver and Neubauer, pp. 78 ff.
R. Sh'lomoh Astruc (14th c.)
My servant shall prosper, or be truly intelligent, because by intelligence man is really man -- it is intelligence which makes a man what he is. And the prophet calls the King Messiah my servant, speaking as one who sent him. Or he may call the whole people my servant, as he says above my people (lii. 6): when he speaks of the people, the King Messiah is included in it; and when he speaks of the King Messiah, the people is comprehended with him. What he says then is, that my servant the King Messiah will prosper.
Driver and Neubauer, p. 129.
Those that are in faovur of the verse being symbolic of the jewish nation (add to later)