Revelation 21:6; I Will Give Unto Him That Is Athirst of the Fountain of the Water of Life Freely
Revelation 21:6 (KJV) And he said unto me, It is done. I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely.
The metaphor of thirst to express an earnest sense of spiritual need comes from Isaiah 55:1 (cf. Psalm 42:1-2; 63:1; Isaiah 12:3; 44:3).
Isaiah 55:1 (KJV) Ho, every one that thirsteth, come ye to the waters, and he that hath no money; come ye, buy, and eat; yea, come, buy wine and milk without money and without price.
Psalm 42:1-2 (KJV) To the chief Musician, Maschil, for the sons of Korah. As the hart panteth after the water brooks, so panteth my soul after thee, O God. My soul thirsteth for God, for the living God: when shall I come and appear before God?
Psalm 63:1 (KJV) A Psalm of David, when he was in the wilderness of Judah. O God, thou art my God; early will I seek thee: my soul thirsteth for thee, my flesh longeth for thee in a dry and thirsty land, where no water is;
Isaiah 12:3 (KJV) Therefore with joy shall ye draw water out of the wells of salvation.
Isaiah 44:3 (KJV) For I will pour water upon him that is thirsty, and floods upon the dry ground: I will pour my spirit upon thy seed, and my blessing upon thine offspring:
Here God uses it in His promise to the faithful – I will give unto him that is athirst of the fountain of the water of life freely.
Three other passages contain the essence of this promise (Revelation 7:17; 22:1; cf. John 4:13-14; 7:37-39; contra Jeremiah 2:13; 17:13).
Revelation 7:17 (KJV) For the Lamb which is in the midst of the throne shall feed them, and shall lead them unto living fountains of waters: and God shall wipe away all tears from their eyes.
Revelation 22:1 (KJV) And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb.
John 4:13-14 (KJV) Jesus answered and said unto her, Whosoever drinketh of this water shall thirst again: But whosoever drinketh of the water that I shall give him shall never thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting life.
John 7:37-39 (KJV) In the last day, that great day of the feast, Jesus stood and cried, saying, If any man thirst, let him come unto me, and drink. He that believeth on me, as the scripture hath said, out of his belly shall flow rivers of living water. (But this spake he of the Spirit, which they that believe on him should receive: for the Holy Ghost was not yet given; because that Jesus was not yet glorified.)
Jeremiah 2:13 (KJV) For my people have committed two evils; they have forsaken me the fountain of living waters, andhewed them out cisterns, broken cisterns, that can hold no water.
Jeremiah 17:13 (KJV) O LORD, the hope of Israel, all that forsake thee shall be ashamed, and they that depart from me shall be written in the earth, because they have forsaken the LORD, the fountain of living waters.
The second occurrence in the verse of the personal pronoun “I” emphasises that this is God’s own promise “I and no other will give.” This is an infinitely better thirst quencher than the cup offered by the harlot Babylon (Revelation 17:4; 18:3) (Ladd).
Revelation 17:4 (KJV) And the woman was arrayed in purple and scarlet colour, and decked with gold and precious stones and pearls, having a golden cup in her hand full of abominations and filthiness of her fornication:
Revelation 18:3 (KJV) For all nations have drunk of the wine of the wrath of her fornication, and the kings of the earth have committed fornication with her, and the merchants of the earth are waxed rich through the abundance of her delicacies.
God’s promise implies a thirst that is ready and eager to accept the benefit that is free and is part of the family privilege (v7). Here God gives the water freely; in Revelation 22:17 the thirsty one receives it freely.
[Robert L. Thomas, Revelation 8-22 – An Exegetical Commentary, Moody, 1995, 448-449]