The phrase laissez-faire is not to be found in the works of Adam Smith, of Ricardo, or of Malthus. Even the idea is not present in a dogmatic form in any of these authors. Adam Smith, of course, was a Free Trader and an opponent of many eighteenth-century restrictions on trade. But his attitude towards the Navigation Acts and the usury laws shows that he was not dogmatic. Even his famous passage about 'the invisible hand' reflects the philosophy which we associate with Paley rather than the economic dogma of laissez-faire.
Ch. 2 - Essays in Persuasion (1931) - The End of Laissez-faire (1926)