John 7:37-39 Out of his belly shall flow rivers

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 shall 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.) 

-John 7:37-39King James Version (KJV)

Apocalypse Explained #622 By Emanuel Swedenborg

622. 

...the "belly" signifies what is interior, because inwardly received and ascertained. The "belly" signifies interior things because the bellystores up the food inwardly, and "food" signifies everything that nourishes the soul; also because the belly, like the bowels, is within or in the midst of the body; for this reason the "belly," and also the "bowels," signify in the Word interior things.

[4] In John: Jesus said, If anyone thirst let him come unto Me and drink. He that believeth on Me, as the Scripture saith, out of his belly shall flow rivers of living water. This He said of the Spirit which they that believe on Him were to receive (7:37-39). 

Thus the Lord describes Divine truth inwardly perceived by those who are in the spiritual affection of truth; such are meant by "those who thirst and come to the Lord and drink;" that such shall have an understanding of Divine truth is signified by "out of his belly shall flow rivers of living water," "riversout of the belly" meaning interior understanding or intelligence, and "living water," Divine truth from the Lord; and as "the Holy Spirit" means Divine truth proceeding from the Lord, it is added "this He said of the Spirit which they that believe on Him were to receive."