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.
The last day of the feast of tabernacles was regarded as a great day, not because of the amount of sacrifices offered because they would offer less on this day. This day was regarded as great because the offering made on this day would be for the people of Israel themselves.
And just as David had done many years previously, they would pour out a water sacrifice.
What Jesus was saying here was that the sacrifices would never be as worthy as people following Him with their hearts. Jesus made an end to the need for sacrifices by being the perfect sacrifice for us all.