In that day when leviathan shall be destroyed, the vineyard (Psa 80:8), the Church of God, purged of its blemishes, shall be lovely in God’s eyes; to bring out this sense the better, Lowth, by changing a Hebrew letter, reads “pleasant,” “lovely,” for “red wine.”
sing - a responsive song [Lowth].
unto her - rather, “concerning her” (see on Isa 5:1); namely, the Jewish state [Maurer].