This chapter Isaiah 12:1-6 is a part of the vision which was commenced in Isaiah 10:5. The prophet had foretold the deliverance of the nation from the threatened invasion of Sennacherib Isaiah. 10; he had then looked forward to the times of the Messiah, and described the certainty, the character, and the consequences of this reign Isaiah. 11. The eleventh chapter closes with a reference to the deliverance of the nation from the oppression of the Egyptians. That deliverance was celebrated with a beautiful ode, which was sung by Miriam and 'all the women,' who 'went out after her with timbrels and with dances' Exodus. 15:1-21. In imitation of that deliverance, Isaiah says, in this chapter, that the deliverance of which he speaks shall be celebrated also with a song of praise; and this chapter; therefore, is properly an expression of the feelings office redeemed people of God, in view of his great mercy in interposing to save them.
It should be read in view of the great and glorious deliverance which God has performed for us in the redemption of his Son; and with feelings of lofty gratitude that he has brought us from worse than Egyptian bondage - the bondage of sin. The song is far better applied to the times of the Messiah, than it could be to anything which occurred under the Jewish dispensation. The Jews themselves appear to have applied it to his time. On the last day of the feast of tabernacles, they brought water in a golden pitcher from the fountain of Siloam, and poured it, mingled with wine, on the sacrifice that was on the altar, with great rejoicing (see the notes at John 7:14, notes at John 7:37). This custom was not required by Moses, and probably arose from the command in Isaiah 12:3 of this chapter. Our Saviour applied it to himself, to the benefits of his gospel, and to the influences of the Spirit John 7; and the ancient Jews so applied it also. 'Why is it called the house of drawing? Because from thence they draw the Holy Spirit; as it is written, "and ye shall draw water with joy from the fountains of salvation."' - ("Jerusalem Talmud" as quoted by Lowth.)

Prophetic hymn of praise for the great mercies vouchsafed to the children of Israel in their deliverance from the great Babylonish captivity, and for redemption by the Messiah, Isaiah 12:1-6.
This hymn seems, by its whole tenor, and by many expressions in it, much better calculated for the use of the Christian Church than for the Jewish, in any circumstances, or at any time that can be assigned. The Jews themselves seem to have applied it to the times of Messiah. On the last day of the feast of tabernacles they fetched water in a golden pitcher from the fountain of Shiloah, springing at the foot of Mount Sion without the city: they brought it through the water-gate into the temple, and poured it, mixed with wine, on the sacrifice as it lay upon the altar, with great rejoicing. They seem to have taken up this custom, for it is not ordained in the law of Moses, as an emblem of future blessings, in allusion to this passage of Isaiah, "Ye shall draw waters with joy from the fountains of salvation," expressions that can hardly be understood of any benefits afforded by the Mosaic dispensation. Our Savior applied the ceremony, and the intention of it, to himself, and the effusion of the Holy Spirit, promised, and to be given, by him. The sense of the Jews in this matter is plainly shown by the following passage of the Jerusalem Talmud: "Why is it called the place or house of drawing?" (for that was the term for this ceremony, or for the place where the water was taken up) "Because from thence they draw the Holy Spirit; as it is written, And ye shall draw water with joy from the fountains of salvation." See Wolf. Curae Philol. in N.T. on John 7:37, John 7:39. - L. The water is Divine knowledge, says Kimchi, and the wells the teachers of righteousness. The Targum renders this in a very remarkable manner: "Ye shall receive with joy (אולפן חדת ulephan chadath) a new doctrine from the chosen among the righteous." Does not this mean the Gospel, the new covenant? And did not the Targumist speak as a prophet?

INTRODUCTION TO ISAIAH 12
This chapter contains a song of praise and thanksgiving for redemption and salvation by Christ, of which the preceding chapter Isaiah 11:1 is a famous prophecy. It begins with an account of the church's former uncomfortable and now comfortable state and condition, Isaiah 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, Isaiah 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, Isaiah 12:3 and then follow certain mutual exhortations to praise, exalt, and glorify Christ, with reasons enforcing them, Isaiah 12:4.

This is a hymn of praise suited to the times of the Messiah.