On the last and greatest day of the feast, Jesus stood up and called out in a loud voice, "If anyone is thirsty, let him come to Me and drink. Whoever believes in Me, as the Scripture has said: 'Streams of living water will flow from within him.'"
In their hunger You gave them bread from heaven; in their thirst You brought them water from the rock. You told them to go in and possess the land which You had sworn to give them.
The LORD will always guide you; He will satisfy you in a sun-scorched land and strengthen your frame. You will be like a well-watered garden, like a spring whose waters never fail.
And on that day living water will flow out from Jerusalem, half of it toward the Eastern Sea and the other half toward the Western Sea, in summer and winter alike.
Significance
No single identifiable OT text (hence 7:38 unique formula "as the Scripture has said"). Clusters multiple water-provision texts. Feast of Tabernacles background (water-pouring ceremony). Fulfilled in gift of Spirit (7:39). Jesus replaces temple as source of living water.