He who believes in Me, as the Scripture has said, out of his heart will flow rivers of living water

John 7:38
He who believes in Me, as the Scripture has said, out of his heart will flow rivers of living water.”

This verse is more than a description of the blessings that will come to the believer. It focuses on the blessing the believer will become for others because out of him, water will flow to provide for other people's needs. This is when God makes us to become like Himself, just like He has poured and emptied Himself for the people and continuously get refreshed again. So we too are being molded in that fashion to enable us to sacrifice ourselves for others' sake.