Leviticus 23:36-37 belongs to the instructions for the Feast of Booths, or Tabernacles, and requires offerings to be presented to the LORD during the festival. The text itself does not specifically institute the later water-pouring ceremony associated with the feast, nor does it directly predict Jesus' invitation to the thirsty. That later Jewish festival practice nevertheless provides important historical background for understanding the imagery used in John's Gospel.
John 7:37 records Jesus standing on the last and greatest day of the feast and crying out, "If anyone thirsts, let him come to me and drink." He then speaks of living water flowing from the believer, which John explains in relation to the Holy Spirit. The connection with Leviticus is therefore primarily one of festival setting and typological development rather than direct prediction. The feast established by the Law becomes the setting in which Jesus presents Himself as the source of the spiritual life and divine provision symbolized by water.