“If a man can’t curse his freinds, whom can he curse?” is allegedly a typical Texan sentiment from Sam Houston.
 
 
August 1869, Overland Monthly and Out West Magazine, South-Western Slang, pg. 125:
As a specimen of Texas ingenuity, or rather perverseness of imagination, take its code of morals, which is embraced in two saying. The first is, “Revolvers make all men equal;” and the second is the famous utterance of Houston, “If a man can’t curse his friends, whom can he curse?”