From the Bible

The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world.
This is he of whom I said, After me cometh a man which is preferred before me: for he was before me.
And I knew him not: but that he should be made manifest to Israel, therefore am I come baptizing with water.
And John bare record, saying, I saw the Spirit descending from heaven like a dove, and it abode upon him.
And I knew him not: but he that sent me to baptize with water, the same said unto me, Upon whom thou shalt see the Spirit descending, and remaining on him, the same is he which baptizeth with the Holy Ghost.
And I saw, and bare record that this is the Son of God.
John 1:29-34