foul and fair 在任何情况下，不管顺利或困难
He's been a good friend through foul and fair.
He had promised that he would be with his sister through fair and foul.
Fair is foul, and foul is fair.
fair /feə/ adj. 公平的;美丽的，白皙
Faint heart never won fair lady.
foul /faʊl/ adj.邪恶的;难闻的，有恶臭的;下流的
If you describe something as foul, you mean it is dirty and smells or tastes unpleasant.
...foul polluted water...恶臭的脏水