You are probably thinking about the foundations of leninism by stalin, specifically the chapter on the national question.
Relevant section being:
The same must be said of the revolutionary character of national movements in general. The unquestionably revolutionary character of the vast majority of national movements is as relative and peculiar as is the possible revolutionary character of certain particular national movements. The revolutionary character of a national movement under the conditions of imperialist oppression does not necessarily presuppose the existence of proletarian elements in the movement, the existence of a revolutionary or a republican programme of the movement, the existence of a democratic basis of the movement. The struggle that the Emir of Afghanistan is waging for the independence of Afghanistan is objectively a revolutionary struggle, despite the monarchist views of the Emir and his associates, for it weakens, disintegrates and undermines imperialism; whereas the struggle waged by such "desperate" democrats and "Socialists," "revolutionaries" and republicans as, for example, Kerensky and Tsereteli, Renaudel and Scheidemann, Chernov and Dan, Henderson and Clynes, during the imperialist war was a reactionary struggle, for its results was the embellishment, the strengthening, the victory, of imperialism. For the same reasons, the struggle that the Egyptians merchants and bourgeois intellectuals are waging for the independence of Egypt is objectively a revolutionary struggle, despite the bourgeois origin and bourgeois title of the leaders of Egyptian national movement, despite the fact that they are opposed to socialism; whereas the struggle that the British "Labour" Government is waging to preserve Egypt's dependent position is for the same reason a reactionary struggle, despite the proletarian origin and the proletarian title of the members of the government, despite the fact that they are "for" socialism. There is no need to mention the national movement in other, larger, colonial and dependent countries, such as India and China, every step of which along the road to liberation, even if it runs counter to the demands of formal democracy, is a steam-hammer blow at imperialism, i.e., is undoubtedly a revolutionary step.
Lenin was right in saying that the national movement of the oppressed countries should be appraised not from the point of view of formal democracy, but from the point of view of the actual results, as shown by the general balance sheet of the struggle against imperialism, that is to say, "not in isolation, but on a world scale"
Imperialism: The Highest Stage Of Capitalism. Lenin 'briefly' defines imperialism as:
Definition
(1) the concentration of production and capital has developed to such a high stage that it has created monopolies which play a decisive role in economic life;(2) the merging of bank capital with industrial capital, and the creation, on the basis of this “finance capital”, of a financial oligarchy;
(3) the export of capital as distinguished from the export of commodities acquires exceptional importance;
(4) the formation of international monopolist capitalist associations which share the world among themselves, and
(5) the territorial division of the whole world among the biggest capitalist powers is completed. Imperialism is capitalism at that stage of development at which the dominance of monopolies and finance capital is established; in which the export of capital has acquired pronounced importance; in which the division of the world among the international trusts has begun, in which the division of all territories of the globe among the biggest capitalist powers has been completed. Essentially once the markets within a nation have developed to the point of monopolies, they must expand to foreign markets. Imperialism can be described as exploitation by foreign capital