The Samaritan woman therefore said to him, "How is it that you, being a Jew, ask for a drink from me, a Samaritan woman?" (For Jews have no dealings with Samaritans.)
Jews have no dealings with Samaritans -- The woman was surprised that Jesus would speak to her, much less ask her for a drink. This parenthetical comment is added for the benefit of John’s non-Jewish readers.