Adam Clarke on Proverbs 14:21

He that despiseth his neighbor sinneth - To despise a man because he has some natural blemish is unjust, cruel, and wicked. He is not the author of his own imperfections; they did not occur through his fault or folly; and if he could, he would not retain them. It is, therefore, unjust and wicked to despise him for what is not his fault, but his misfortune.

But he that hath mercy on the poor - Who reproaches no man for his poverty or scanty intellect, but divides his bread with the hungry - happy is he; the blessing of God, and of them that were ready to perish, shall come upon him.