The classical source: Adam Smith in his 1776 An Inquiry into the Nature and Causes of the Wealth of Nations. Smith's concern for the poor there is palpable and undeniable. Now some scholars argue that, partly because of that, Smith would not quite qualify as a right-of-center thinker (Samuel Fleischacker,for example, but there are many others), but I think Smith's defense of free trade, markets, and limited government do qualify him. He is not an anarchist or even a libertarian, and he does not subscribe to a theory of natural rights that, as in Locke or Nozick, give principled restrictions on state activity: Smith is too practical and pragmatic for that. But that makes him what is usually called a "classical liberal," not a progressive liberal.
The contemporary source: Deirdre N. McCloskey's The Bourgeois Virtues: Ethics for an Age of Commerce. McCloskey's argument is that capitalist institutions are not amoral but are, instead, positively encouraging of virtue. But a large part of her argument in that book is that capitalism has brought substantial and often unappreciated benefits to millions of people, including especially the poor. McCloskey draws explicitly on Smith in making her case.