相传古爱尔兰曾发生过这样的事情，凯尔国王率兵入侵阿萨，阿萨国王派兵团扼守关口，不料这军团受了敌方贿赂，将关口拱手相让，结果不战而败。所以人们后来用sell the pass（出卖关口）来比喻出卖、背叛或放弃立场的行为。

【例句】
We were astonished when he sold the pass and voted against the Bill of Rights.
他放弃立场，投票反对人权法案，令我们大感惊讶。

Those soldiers who sold the pass were punished later.
那些出卖立场的士兵，后来都被惩罚。