Jesus answered and said unto her, If thou knewest the gift of God, and who it is that saith to thee, Give me to drink; thou wouldest have asked of him, and he would have given thee living water. If thou knewest the gift of God - Δωρεαν signifies a free gift. A gift is any thing that is given, for which no equivalent has been or is to be returned: a free gift is that which has been given without asking or entreaty. Such a gift of kindness was Jesus Christ to the world, John 3:16; and through him comes the gift of the Spirit, which those who believe on his name were to receive. Christ was not an object of desire to the world - no man asked for him; and God, moved thereto by his own eternal mercy, freely gave him. Through this great gift comes the Holy Spirit, and all other gifts which are necessary to the salvation of a lost world.
Living water - By this expression, which was common to the inhabitants both of the east and of the west, is always meant spring water, in opposition to dead, stagnant water contained in ponds, pools, tanks, or cisterns; and what our Lord means by it is evidently the Holy Spirit, as may be seen, John 7:38, John 7:39.
As water quenches the thirst, refreshes and invigorates the body, purifies things defiled, and renders the earth fruitful, so it is an apt emblem of the gift of the Holy Ghost, which so satisfies the souls that receive it that they thirst no more for earthly good: it purifies also from all spiritual defilement, on which account it is emphatically styled the Holy Spirit; and it makes those who receive it fruitful in every good word and work.