The Feast of Tabernacles was celebrated with certain festival rituals. One was a solemn procession each day from the temple to the Gihon Spring. A priest filled a gold pitcher with water while the choir sang Isaiah 12:3. Then they returned to the altar and poured out the water. This ritual reminded them of the water from the rock during the wilderness wanderings (Num.20:8-11; Ps. 78:15-16). It also spoke prophetically of the coming days of Messiah (cf. Zech.14:8, 16-19). The Feast’s seventh and last day was its greatest (cf. Lev. 23:36). Jesus stood, in contrast to the Rabbis’ usual position of being seated while teaching. Said in a loud voice (cf. John 1:15; 7:28; 12:44) was a way of introducing a solemn announcement. His offer Come to Me and drink, was an offer of salvation (cf. 4:14; 6:53-56). (The Bible Knowledge Commentary of the N.T., by Walvoord and Zuck, ©1985, p. 301)