Patriotism is the last refuge of a scoundrel.

johnson patriotism is the last refuge of a scoundrel wist.info quote

Samuel Johnson (1709-1784) English writer, lexicographer, critic
Comment (1775-04-07)
    (Source)

In James Boswell, The Life of Samuel Johnson (1791). The full quote:

Patriotism having become one of our topicks, Johnson suddenly uttered, in a strong determined tone, an apophthegm, at which many will start: "Patriotism is the last refuge of a scoundrel." But let it be considered, that he did not mean a real and generous love of our country, but that pretended patriotism which so many, in all ages and countries, have made a cloak of self-interest.

Ambrose Bierce wrote in his Devil's Dictonary, under "Patriotism," "In Dr. Johnson's famous dictionary patriotism is defined as the last resort of a scoundrel. With all due respect to an enlightened but inferior lexicographer I beg to submit that it is the first."

The saying is famous and noteworthy enough that many others have riffed on it beyond Bierce: see Wilde (and again), Roosevelt, Broun, Asimov, Lewis, and Ehrenreich.