"Jesus saith unto her, I that speak unto thee am He. (John 4:26). 
He gave evidence here that He was the Messiah.
This was the design of
John in writing this gospel.
He has therefore recorded this narrative.
--We see our duty.
It
is to seize on all occasions to lead sinners to the belief that Jesus
is the Christ, and to make use of all topics of conversation to teach
them the nature of religion.
*There never was a model of so much wisdom
in this as the Savior, and we shall be successful only as we diligently
study His character."
Barnes Notes