John Gill's Exposition of the Whole Bible
Isaiah 5:1
Now will I sing to my well beloved,.... These are the words of the Prophet Isaiah, being about to represent the state and condition of the people of Israel by way of parable, which he calls a song, and which he determines to sing to his beloved, and calls upon himself to do it; by whom he means either God the Father, whom he loved with all his heart and soul; or Christ, who is often called the beloved of his people, especially in the book of Solomon's song; or else the people of Israel, whom the prophet had a great affection for, being his own people; but it seems best to understand it of God or Christ:
a song of my beloved; which was inspired by him, or related to him, and was made for his honour and glory; or "a song of my uncle" q, for another word is used here than what is in the preceding clause, and is rendered "uncle" elsewhere, see Leviticus 25:49 and may design King Amaziah; for, according to tradition, Amoz, the father of Isaiah, was brother to Amaziah king of Judah, and so consequently Amaziah must be uncle to Isaiah; and this might be a song of his composing, or in which he was concerned, being king of Judah, the subject of this song, as follows:
touching his vineyard; not his uncle's, though it is true of him, but his well beloved's, God or Christ; the people of Israel, and house of Judah, are meant, comparable to a vineyard, as appears from Isaiah 5:7 being separated and distinguished from the rest of the nations of the world, for the use, service, and glory of God.
My beloved hath a vineyard in a very fruitful hill; or, "in a horn, the son of oil" r; which designs the land of Israel, which was higher than other lands; and was, as some observe, in the form of a horn, longer than it was broad, and a very fruitful country, a land of olive oil, a land flowing with milk and honey, Deuteronomy 8:7. The Targum is,
"the prophet said, I will sing now to Israel, who is like unto a vineyard, the seed of Abraham, my beloved, a song of my beloved, concerning his vineyard. My people, my beloved Israel, I gave to them an inheritance in a high mountain, in a fat land.''
q שירת דודי "canticum patruelis mei", V. L. r בקרן בן שמן "in cornu, filio olei", V. L.