We read in Jn 7: 37-38:
"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, 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.’”
Going back to Old Testament, we read at Isaiah 58:11:
"And the Lord will guide you continually and satisfy your desire in scorched places and make your bones strong; and you shall be like a watered garden, like a spring of water, whose waters do not fail.”
See that the verses of Isaiah make a good match for Jn 7:38, not a perfect match though, in that the words `living water' are missing from Isaiah.
My question therefore is: Which, according to the Catholic Church, is the writing in the Old Testament that Jesus is referring to in Jn 7:38?