This chapter contains a song of praise and thanksgiving for redemption and salvation by Christ, of which the preceding chapter Isa 11:1-16 is a famous prophecy. It begins with an account of the church's former uncomfortable and now comfortable state and condition, Isa 12:1 the foundation of whose comfort was Christ her salvation and strength, and so her song, which engaged her trust, and dispelled her fears, Isa 12:2 hence encouragement to others to apply to the fulness of Christ for grace, and fresh supplies of it, to be had with joy, Isa 12:3 and then follow certain mutual exhortations to praise, exalt, and glorify Christ, with reasons enforcing them, Isa 12:4-6.