Read John 7:37-39
7:37 On the last day of the festival, the great day, while Jesus was standing there, he cried out, "Let anyone who is thirsty come to me,
7:38 and let the one who believes in me drink. As the scripture has said, 'Out of the believer's heart shall flow rivers of living water.'"
7:39 Now he said this about the Spirit, which believers in him were to receive; for as yet there was no Spirit, because Jesus was not yet glorified.