Jamieson, Fausset and Brown on Matthew 5:46

46. For if ye love them which love you, what reward have ye? do not even the publicans the same?--The publicans, as collectors of taxes due to the Roman government, were ever on this account obnoxious to the Jews, who sat uneasy under a foreign yoke, and disliked whatever brought this unpleasantly before them. But the extortion practiced by this class made them hateful to the community, who in their current speech ranked them with "harlots." Nor does our Lord scruple to speak of them as others did, which we may be sure He never would have done if it had been calumnious. The meaning, then, is, "In loving those who love you, there is no evidence of superior principle; the worst of men will do this: even a publican will go that length."