We might at first glance think that a reference to a “spring” is unnecessary since it is enough for the thirsty to receive water (and where it comes from is not so important). In point of fact, however, the source of the water that is needed to satisfy thirst in the wilderness of this life is highly important (recall Revelation 12:15!), and Jesus has said that he himself (in his out-poured Spirit) is the spring of living water (John 7:37–39; John 4:14). With the present phrase, then, John is reminding his readers of Jesus’ words as recorded in his earlier gospel.
6 And he said to me, “It is done! I am the Alpha and the Omega, the beginning and the end. To the thirsty I will give from the spring of the water of life without payment.