… is from Book V, Chapter 2 – on page 879, Vol. 2, of the 1981 Liberty Fund edition – of Adam Smith’s 1776 An Inquiry Into the Nature and Causes of the Wealth of Nations:
The gains of alien merchants were looked upon more unfavourably than those of English merchants. It was natural, therefore, that those of the former should be taxed more heavily than those of the latter. This distinction between the duties upon aliens and those upon English merchants, which was begun from ignorance, has been continued from the spirit of monopoly, or in order to give our own merchants an advantage both in the home and in the foreign market.