Matteo 5:47

And if ye salute your brethren only, what do ye more than others? Do not even the publicans so?

That is the usual, the customary way of dealing in the world: Kind deeds are rewarded with kind deeds, friendly words are given in return for friendly words. That is the height of human morality. The word "salute" may be taken in its literal sense, as a mere greeting, for even so much the Jews denied the Gentiles. Or it may imply friendly relations and a readiness to serve, as became those that were united in the same confession.

Outside of that they knew nothing, more they refused to do, John 4:9 b. Such a low moral level is not for the disciples of Christ. He expects them to distinguish themselves above the average morality, to carry out the ambition to excel, actually to be superior to a spirit characterized by smallness and meanness. The latter spirit might be expected in the publicans, the tax-collectors of Palestine, who were heartily disliked as being the representatives of the Roman power, and for their cheating and exactions.

It is not a Pharisaic pride and arrogance that the Lord wishes to awaken, but the earnest desire to be elevated above a mere customary etiquette, which may become the most refined form of cruelty. A significant fact: Jesus finds something good even in the social outcasts!