37 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.
38 He that believeth on me, as the scripture hath said, out of his belly show flow
rivers of living water.
39 (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.)
belly: heart
7:38 – Jesus used the term living water in 4:10 to indicate eternal life.
Here he uses the term to refer to the Holy Spirit.
The two go together: wherever the Holy Spirit is accepted, he brings eternal life.