three stringent rules for living

From: George Carpozi Jr., The John Wayne Story, Arlington House: New Rochelle, NY (1972), page 17:

Clyde Morrison [John Wayne's father] was of Scottish descent... [John] Wayne describes his father as the "kindest, most patient man [he] ever met," saying that the elder Morrison never had an unkind thought in his mind and rarely spoke harshly to his son or anyone else. Nor did he ever lecture young Marion [John Wayne]. But he did teach him three stringent rules for living which have the ring of orders tumbling from the lips of Davy Crockett in the nineteenth century:
1. Always keep your word.
2. A gentleman never insults anybody intentionally.
3. Don't go around looking for trouble. But if you ever get in a fight, make sure you win it.