John 7:37 “On the last day, that great day of the feast, Jesus stood and cried out, saying, “If anyone thirsts, let him come to me and drink.”
"On the last day, the great day of the feast"
The Feast of Sukkoth (Tabernacles or Booths)
The Feast of Tabernacles, known in Hebrew as “Sukkoth” (Booths), also called Ingathering (end of the year). It was the last of the divinely appointed "moadeem" (sacred festivals) under the O.T. It was made to commence on the 15th day of the 7th month (5 days after yom kippur)
The Jews were commanded to make little booths beside their houses to dwell in throughout the week of the feast and they do this to the present day. They make their booths with thatched (branches and leaves woven together) so that it would not be permanent, but temporary. The roofs had space in-between the thatches so that at night they could look up and see the stars which was a reminder of the 40 year wanderings of their fathers in the wilderness.
They also had to leave enough space in the walls so that the wind could blow through and as they felt the wind they were reminded how that their fathers were exposed to the perils of the wilderness for 40 years and were yet preserved by God.
During N.T. times the priests, for each of the first seven days of the feast in Jerusalem, would go down to the pool of Siloam in a religious procession with large water jugs and there at the pool of Siloam they would fill the water jugs and come up the many steps to the Temple mount commemorating the long expected anticipation of the promise given through the prophet Isaiah (Heb. Yeshayahu):
Isa 12:1-4 “And in that day you will say: "O LORD, I will praise You; though You were angry with me, your anger is turned away, and You comfort me. Behold, God is my salvation, I will trust and not be afraid; 'For YAH, the LORD, is my strength and song; he also has become my salvation.'" Therefore with joy you will draw water from the wells of salvation. And in that day you will say: "Praise the LORD, call upon His name; declare His deeds among the peoples, make mention that His name is exalted.”
As they approached with the water jugs the people would burst forth in singing the "Hallel Psalms" (Ps 113-118) and as the people were praising the Lord they would pour out these water jugs upon the Pavement and as the water poured they were reminded of how God miraculously provided water in the wilderness out of the Rock, and will also one day pour water from heaven on their thirsty souls through the Messiah.
On the Eighth day, the last day, called "the great day of the feast" the priests made no procession and poured no water onto the pavement and this too was very significant, because it symbolized the fact that God had fulfilled the promise to their fathers, He had now brought them into this land that was well watered, flowing with milk and honey, they no longer needed the miraculous supply out of the Rock.
It was on this day the last day that Jesus stood and cried out: "If anyone thirsts, let him come to Me and drink. He who believes in Me, as the Scripture has said, out of his heart will flow rivers of living water."
It is interesting to note that it was on this day that they sang the marvelous “hallel psalms” of praise, which conclude with this passage Ps. 118:22 “.. and You have become my salvation, the Stone which the builders rejected has become the chief cornerstone .. and blessed is He who comes in the name of the Lord.”
The historical background sheds much light on the meaning. Jesus, their promised Messiah was standing in their midst as they were performing the ceremony and WAS fulfilling the Scripture and the promise spoken through Isaiah that the Lord would become their salvation (incarnate) and the water was always used as a symbol in Judaism as that which “comes from above” and is identified with Messiah “the coming One” (Heb. Haba”) throughout.
Bibliography on Ancient Customs
The Art of Ancient Egypt, Revised by Robins, 272 Pages, Pub. 2008