Upon this - At this time.
Marvelled - Wondered. They wondered because the Jews had no contact with the Samaritans, and they were surprised that Jesus was engaged with her in conversation.
Yet no man said - No one of the disciples. They had such respect and reverence for him that they did not dare to ask him the reason of his conduct, or even to appear to reprove him. We should be confident that Jesus is right, even if we cannot fully understand all that he does.