https://www.presidency.ucsb.edu/documents/farewell-address

"The unity of government which constitutes you one people is also now dear to you. It is justly so, for it is a main pillar in the edifice of your real independence, the support of your tranquillity at home, your peace abroad, of your safety, of your prosperity, of that very liberty which you so highly prize. But as it is easy to foresee that from different causes and from different quarters much pains will be taken, many artifices employed, to weaken in your minds the conviction of this truth, as this is the point in your political fortress against which the batteries of internal and external enemies will be most constantly and actively (though often covertly and insidiously) directed, it is of infinite moment that you should properly estimate the immense value of your national union to your collective and individual happiness; that you should cherish a cordial, habitual, and immovable attachment to it; accustoming yourselves to think and speak of it as of the palladium of your political safety and prosperity; watching for its preservation with jealous anxiety; discountenancing whatever may suggest even a suspicion that it can in any event be abandoned, and indignantly frowning upon the first dawning of every attempt to alienate any portion of our country from the rest or to enfeeble the sacred ties which now link together the various parts."