| Gill's Exposition of the Entire Bible And if ye do good to them which do good to you,.... As one good turn deserves another: what thank have ye? what grace or goodness is there in such an action? what glory or merit is there in it? for sinners also do even the same: wherefore no man should conclude himself a righteous man, or better than sinners, on such an account: this is to be found among the worst of men, and is natural to them, unless they are brutes indeed, to be kind to such as are kind to them. And yet, this was the whole of the doctrine of the Jews about doing good to men: for so they say (u), "an Israelite is obliged to do good to an Israelite his companion, and to lend without usury: this is kindness and goodness, and a greater good it is than a gift; for many men are ashamed to take a gift, and are not ashamed to take a loan: but not so an Israelite to a Gentile; for he is not bound to do good, or show kindness to him, or to lend him his money freely; for many of them hate the Israelites; but it must be owned, that if a Gentile does a kindness, or good, to an Israelite; the Israelite is also bound to show kindness to him, and do him good.'' In direct opposition to such narrow sentiments does our Lord deliver himself in this, and the following verses. (u) Kimchi in Psal. xv. apud Huls. Theolog. Jud. par. 1. p. 420.
Geneva Study BibleAnd if ye do good to them which do good to you, what thank have ye? for sinners also do even the same.
People's New Testament 6:33 If ye do good, etc. See PNT Mt 5:44.
Matthew Henry's Concise Commentary6:27-36 These are hard lessons to flesh and blood. But if we are thoroughly grounded in the faith of Christ's love, this will make his commands easy to us. Every one that comes to him for washing in his blood, and knows the greatness of the mercy and the love there is in him, can say, in truth and sincerity, Lord, what wilt thou have me to do? Let us then aim to be merciful, even according to the mercy of our heavenly Father to us. | 
